DD's report on oil

 

I am not a lubrication, filtering, chemical or mechanical engineer. I have a degree in engineering, but I studied electrical engineering. I now study physics. You may feel free to question my abilities to gather facts and draw conclusions in the area of oils and filters. In any case, this is a write up of what I learned in about 60 hours of research on this topic. My only interest is having my motorcycle run forever, never break, and be easy to maintain.

Why do we need oil?
We put oil in our engines to serve several purposes. First, obviously, oil acts as a lubricant. If your engine is operating correctly, there is almost no metal to metal contact - everything is riding on a thin film of oil. However, oil has several other important jobs to do. Oil circulates throughout your engine, and cools parts that cannot get near a water jacket. For example, it's becoming common in sport bikes to spray oil on the underside of the piston to cool it. There are no water jackets at all in your transmission. Motorcycle transmissions are oil cooled. Your piston rings do not do a perfect job of sealing. Some combustion by products will slip past the rings into the engine. This can be little particles of carbon. Remember, diamond is carbon that was combined under heat and pressure. These little carbon particles can be quite damaging to your engine. Another job of your oil is to hold these particles in suspension until the oil filter can grab them. Also, if your gasoline has sulpher in it (it does), this sulpher can react with water and oxygen to make sulpheric acid. This is some stuff that is seriously bad for your engine. Your oil has special ingredients in it called buffers to neutralize the sulpheric acid. Finally, your engine can get internal build ups of tars, waxes, and other gunk. Your oil has solvents to try to dissolve this stuff and get and keep your engine clean.

Where Oil Comes From
Most of the bio-mass on earth is single cell plants and microscopic critters in the ocean. When these die, they sink to the bottom. Often they fall into a deep crevasse or trench, where they may become covered up by an underwater landslide. After a couple hundred million years of high pressure and no air, the critters get squished into oil. So, oil isn't really "dead dinosaurs," but Sinclair Oil stations just wouldn't be the same with a picture of algie on their sign. Today we like to find this stuff, pump it to the surface, and burn it.

The oil we pump to the surface is a mixture of gasoline, kerosene, light weight lubricating oil, motor oil, gear oil, tars, paraffins, waxes, asphalt, sand, dirt, organic stuff (called aromatics) and the occasional dead cockroach. We call this stuff crude oil, for reasons that I think are now self-explanitory. The oil companies have the singularly smelly job of separating the crude oil into its component parts. A hundred years ago we would just heat the stuff up in a complicated still, and catch stuff that boiled off at different temperatures. Fifty years ago we started processing the crude oil with clay and solvents to do a more precise job. Today, we use very complicated systems where we heat the crude oil to precise temperatures, put it under high pressure, and bubble hydrogen and other stuff through it. The idea of all this is to try to get pure chemicals out of this stuff that we just found laying around in the desert.

Most motor oil has a lot of different chemicals in it with very different properties. The temperature at which the oil will start burning, called the flash point, is determined by the chemicals that burn at the lowest temperature. The higher the flash point, the more stable the oil is at high temperatures, and the less oil your engine will burn. The pour point is the temperature at which the oil stops flowing like a liquid. The lower this number is, the better protected your engine is when it's cold. The thickness of the oil, that is the resistance the oil offers to motion, is called the viscosity. The viscosity depends on all of the various chemicals in the oil and how they react to each other and to heat. Importantly, as the oil heats up, it thins out, that is the viscosity goes down. The better the oil is at retaining its viscosity at high temperatures, the higher the viscosity index. All of these properties depend on all the chemicals in the oil. If you could get only one precise kind of molecule out of the raw oil, you could do a lot better than you can do with a mix.

Refining Oil
The oil product you buy starts as a base oil. The base oil makes up about 85% of the oil you buy. The base oil can be refined from crude oil, chemically (synthetically) manufactured, or a blended combination.

Base oils that are refined from crude oil are colorless and pretty much odorless and are sold to the public as mineral oil. The curde oil is a combination of a lot of different chemicals, ranging from light gasolive types of fuels to waxes and tars. When you heat the crude oil, the gasolene and diesel oil boil off pretty early. Unfortunately, the mineral oil, paraffin, wax and tar molecules are all hooked up with each other, and it's not so easy to seperate them from each other. There are currently 5 classes of base oil, called Group I, II, III, IV, and V. Group I oil is refined the old-fashioned way using clay and solvents, and is used in about 2/3 of the oil sold in America today. Group I oils contain a fair amount of pariffin and wax. These molecules cause several problems in an engine: they sometimes fall out of solution, leading to buildups in your engine that must be cleaned out somehow. Also, as these molecules get hot they thin out quite a bit, much more than mineral oil, so they make the oil's high temperature performance rather poor.

In 1990, Chevron developed a new method of refining base oils called Hydrocracking, where you process the raw oil at high temperatures and pressures with hydrogen. In Hydrocracking, many of the pariffin and wax molecules are broken up into mineral oil molecules, which increases the performance of the base oil dramatically. Base oils made with this method are called Group II, and are significantly more pure and have higher performance than Group I base oils. Chevron Delo 400, Mobil Delvac 1300, and Shell Rotella are made from pure Group II oils. Motor oils made with hydrocracked base oils leave far fewer wax and tar deposits in your engine, and have much better high temperature performance than group I oils.

Since 1990, Chevron's process has been improved. By increasing the severity of the hydrocracking process, raising the temperature and pressure to break up more and more of the unwanted wax and pariffin molecules, the viscosity index (VI) can be improved further. The VI tells us how much the oil thins out as it gets hot. Oils with higher VIs maintain their viscosity better at high temperatures. If the VI is 90 to 100, we call it Group II; if it's refined to a VI of 110 to 115 we call it Group IIa. In the late '90s, an even more involved process was invented yielding base oils with VIs over 120. These base oils are called Group III or "unconventional base oils." The higher the VI, the fewer additives are necessary to achieve the required viscosity. For example fewer additives are needed to turn a Group III base oil into 10w-40 than are required for Group II base oils.

These Group III oils have properties approaching synthetics, so long as the temperature is above about 40. Group III based oils are often claimed to not perform as well as synthetics in a couple ways: their low temperature performance is not nearly as good, it is sometimes claimed on the basis of the "ball bearing test" that they offer lower impact resistance, and since their flash point is slightly lower it is claimed that they burn off more easily. However, most modern engines are water-cooler, so it's hard to see how the slightly better flash points of the synthetics ever come into play. I personally don't make a habit of dropping a handful of ball bearing into my oil pan, so I'm not completely clear on what the impact tests mean to me. The low temperature performance of the Group III oils can be improved enormously by blending in a relatively small amount of synthetic base stock.

In the late 1990s, Castrol started selling an oil made from Group III base oil and called it SynTec Full Synthetic. Mobil sued Castrol, asserting that this oil was not synthetic, but simply a highly refined petroleum oil, and therefore it was false advertising to call it synthetic. In 1999, Mobil lost their lawsuit. It was decided that the word "synthetic" was a marketing term and referred to properties, not to production methods or ingredients. Castrol continues to make SynTec out of Group III base oils, that is highly purified oil with most all of the cockroach bits removed.

Shortly after Mobil lost their lawsuit, most oil companies started reformulating their synthetic oils to use Group III base stocks instead of PAOs or diester stocks as their primary component. Most of the "synthetic oil" you can buy today is actually mostly made of this highly-distilled and purified dino-juice called Group III oil. Group III base oils cost about half as much as the synthetics. By using a blend of mostly Group III oils and a smaller amount of "true" synthetics, the oil companies can produce a product that has nearly the same properties as the "true" synthetics, and nearly the same cost as the Group III oil. In fact, Mobil-1 is now primarily made from Group III unconventional base oils, exactly the stuff Mobil was claiming was not really synthetic. The much more expensive traditional synthetics are now available in their pure forms only in more expensive and harder to obtain oils.

Synthetic Oils
Synthetic oils were originally designed for the purpose of having a very pure base oil with excellent properties. By starting from scratch and building up your oil molecules from little pieces, you can pretty much guarantee that every molecule in the oil is just like every other molecule, and therefore the properties are exactly what you designed in, not compromised by impurities from dead cockroach shells or whatever. Synthetics were thus originally a reaction to the relatively poor refining processes available from about 1930 to about 1990. The original synthetics were designed for the Army Air Force in WW II. They simply could not make their high-performance turbo-charged radial engines stay alive on the available motor oils of the time.

One process for making synthetic base oils is to start with a chemical called an olefin, and make new molecules by attaching them to each other in long chains, hence "poly." The primary advantage of Poly-Alpha-Olefin "PAO" base oil is that all the molecules in the base oil are pretty much identical, so it's easy to get the base oil to behave exactly as you like. PAOs are called Group IV base oils.

Another type of base oil made from refined and processed esters and is called Group V. Esters start life as fatty acids in plants and animals, which are then chemically combined into esters and diesters. Group V base stocks are the most expensive of all to produce. However, the esters have very significant solvent properties - an ester base oil all by itself will do a very decent job of keeping your engine clean. So, people who are serious about making a superior oil will usually mix some Group V oils into their base stock.

Finally, there are new chemicals emerging which are made from liquefied natural gas called GTL (gas to liquid) base oils. These will perhaps be called Group VI, and many people think they will become an important part of the oils you buy within a few years. Natural gas is primarily made up of only one type of molecule, so the refining is already done for you. Most oil wells throw off a lot of natural gas. In many cases, it's more expensive to transport this gas to a large city than the gas is worth, so it's just burned off. For example, Iran burns off enough natural gas each day to power their entire country, electricity, cars, ships, airplanes, the whole thing. So the next time you hear Iran's nuclear reactors are purely for peaceful production of energy, you can wonder like the rest of us why a country that burns off more than their entire energy needs must spend tens of billions of dollars developing alternative energy sources. Well, anyway, natural gas is a chemical looking for a use. All you have to do is chemically attach these molecules to each other to turn them into quite pure oil stocks.

"Semi-synthetics" are oils which are a blend of petroleum oil and no more than 30% synthetic oil. If the manufacturer adds no more than 30% synthetic oil and does not change the additive package, they do not have to recertify the oil. These days, since everyone has agreed that Group III base oils are "synthetic," I'm not sure "semi-synthetic" means anything at all.

Making Multi-Grade Oil
A simple standard oil, for example a pure base stock, would be a single weight, like 30 weight. This pure oil would have no detergent additives to keep the engine clean. This oil would be relatively thick and difficult to pour at room temperature, and would thin out as the motor heated up. On a very cold day, say 10 below freezing, this oil would thicken to the point where you could not start your motor, and if you did, the oil pump could not pump the oil around to protect your motor. It used to be that to start their diesel trucks in the winter, truckers would add kerosene to their oil to thin it out. Then they had to hope the kerosene would burn off before it did any real damage. Today, synthetic oils that are rated 0W-40 flow normally down to 65 below zero and remove the need for engine block heaters or adding kerosene.

An oil sold as 10w-40 is no thicker than 10 weight oil under Winter (10w) conditions, meaning at 32 Fahrenheit. The 40 means it is no thinner than 40 weight oil at 212 Fahrenheit. So, the first number tells us the performance of the oil at the temperature of freezing water, and the second number tells us the performance at the temperature of boiling water. The chemicals added to the oil to accomplish this are called Viscosity Index Improvers (VIIs).

To make a 10w-40 oil, the manufacturer would start out with a 10 weight oil as the base stock. All by itself, this oil would thin out so much at normal operating temperatures that the oil film would be useless. So, they add these very special very long molecules, the VIIs. The VII molecules are as much as 1000 times as long as an oil molecule. The VII molecules curl up in a little ball at room temperature, but as the temperature gets higher they uncurl and stretch out, like a cat sleeping in the sunlight. The more stretched out the molecule is, the more it impedes the normal flow of the oil, thus raising the effective viscosity. Now, this sounds just a little too good to be true. Well, there are two catches: first, these molecules are not lubricants, so the more of them that you add the less oil you have sitting around lubricating things. Secondly, these VII molecules can be broken into pieces by various pressures and forces, like being squeezed through the transmission gears in a motorcycle. Every time a VII molecule gets broken, the oil loses some of its high temperature viscosity. Synthetic oils made from pure PAOs and/or Diesters typically have very few VIIs, so these oils are far less subject to viscosity breakdown due to shearing of the VII package. As a result, synthetics are far more stable in a motorcycle engine.

10w-30 oil increases its viscosity at high temperatures by a factor of three, which requires a significant amount of these VII molecules. 10w-40 oil increases its high temperature viscosity by a factor of four, which requires even more even longer molecules. 20w-50, which sounds a lot like 10w-40, only increases its high temperature viscosity by a factor of two and a half, so it requires fewer of these molecules than even 10w-30. 15w-40 also increases its high temperature viscosity by about two and a half, so this oil is also substantially more stable than 10w-40. Most passenger car oils today use inexpensive VII molecules that break apart relatively easily. Conversely, most diesel engine oil VIIs are chosen from more expensive chemicals that are more shear stable, since an oil change in a large diesel is expected to last for 15,000 to 150,000 miles.

In 1994, Dr. John Woolum tested the viscosity of several 10w-40 oils in his motorcycle. He found that all of the petroleum oils had lost highly significant amounts of viscosity within 1500 miles. Only Mobil-1 held up in his test. I have personally tested Delvac-1 synthetic in my ST1300. It was 5w-40 when I put it in, and 5w-25 9,200 miles later. By 1500 miles, the petroleum oils Dr. Woolum tested were at 10w-25. By contrast, Dr. Woolum tested a petroleum oil in his Honda Accord. After 3600 miles, the 10w-40 oil was 10w-37. Motorcycles are indeed significantly harder on their oils than cars.

You might ask, if these viscosity index improvers are so expensive and fragile, why have them? Why not just run a straight 30 weight oil? If you live somewhere where the temperature never changes, like Maui, maybe that's a good idea. However, if your engine will ever see temperatures below 60 degrees or above 100 degrees, it's important to have a multi-weight oil. Multi-weight oils offer far superior protection during a cold engine start on a cold morning, and they also offer superior protection if your engine oil ever gets above about 230. Of course, some old timers will tell you, "I always ran straight 50 weight oil. Yup. That was the stuff. All these new-fangled fancy oils, forget it, it's just marketing hype. All you need is straight 50 weight." Well, that may have been true when motorcycles were 1500ccs and made 18hp. Today, when you can casually buy an engine that makes 150hp per liter, things are just a little different.

Viscosity is not actually measured in "weights", but rather in units called "Stokes." If you're a famous scientist they name a unit after you, except for poor Albert who is considered famous enough all by himself. Stokes was a guy who worked on fluid flow. For oils, we use a hundredth of a Stoke, called a centi-Stoke, abbreviated cSt. "Weights" are a classification invented by the American Petroleum Institute (API). 10 weight oil refers to oils within a range of viscosities, so two different brands of 10 weight oil might actually be quite different. 75 weight gear oil is actually about the same viscosity as 10 weight motor oil. Don't ask me why, I'm not a petroleum engineer; although some might argue that I do belong in an institution.

Motor Oil Additive Packages
In addition to the base stock oil, oil manufacturers add what's called an additive package. Additive packages are typically not made up by the oil companies, but rather by a few companies that then sell them. Additive packages contain several different chemicals with several different purposes. Here's what the additive package is supposed to do for you:

One component is detergents and dispersants. These chemicals are designed to hold onto foreign particles and chemicals in your engine, and sometimes break them into smaller pieces. These foreign chemicals may be combustion by products, or junk that slipped past your air filter. If the particles are large enough, then they will eventually be grabbed by the oil filter and taken out of circulation.
Another component is buffers. This is typically calcium, magnesium, or boron. These chemicals are present to neutralize any acids which form in your engine. Acids are bad for your bearings and other important thingies.
Your additive package will include solvents to break up deposits of tar and wax. In a premium oil, some of the base stock be Group V diesters to help the solvent package. Where did the tar and wax come from? Remember, when you opened up your $1.09 quart of Spiffo-Magic SuperLube, you got oil, additives, tar, paraffin, wax, asphalt, ash, aromatics (sounds like perfume when they say that, doesn't it?), and the occasional stray bit of cockroach shell.
Another component is emergency lubricants. This is typically zinc, phosphorous, and molybdenum. These chemicals are present in case your oil film completely breaks down, due to extreme temperatures or pressures. These chemicals are supposed to be a last resort defense against metal to metal contact in your engine.
The Viscosity Index Improvers are part of the additive package. As we learned above, these chemicals are present to make your oil stay thick at high temperatures.
Finally, corrosion inhibitors. These chemicals are supposed to keep your oil from oxidizing or otherwise breaking down due to time or contamination. Yes, it's true, now even your oil has to take antioxidants.
The additive package is made to make the finished oil product meet one of the certifications. There are two classes of certification: S, for Service, and C, for commercial. The certification standards are maintained by the API, the American Petroleum Institute. Over the years, the API has improved and changed these standards. The most current S standards are SJ and SL. These standards differ from earlier standards like SH by lowering phosphorus to improve catalytic converter life, and increasing molybdenum to lower internal engine friction and improve gas mileage. Phosphorus was originally added to oils to help protect high pressure areas like cam lobes and crankshaft bearings, so lowering phosphorus levels is a compromise of lower pollution, perhaps at the expense of engine life. Molybdenum is added to improve fuel economy due to the federal CAFE (Corporate Average Fuel Economy) standards, thereby helping GM and Ford keep selling large V8s to the American public, but can perhaps cause problems in engines with wet clutches. Most S additive packages are also designed to be inexpensive so that the resulting oil can be sold at a low price. SJ and SL oils are both low phosphorus; SL oils which are labeled "energy conserving" are high molybdenum. SH certified oils are probably the best of the S oils for motorcycles, but you pretty much can't buy them anymore.

The additive packages sold for C (commercial) certification are designed to promote engine life. The additive packages for C rated oils contain extra buffers and detergents to keep the engine clean and free of acids. Generally, C rated oils are far better than S oils at holding and dispersing combustion byproducts and other contaminants, and at not becoming acidic. Traditionally these oils are primarily used in diesel motors, which are very expensive and are expected to last a million miles or more. When an engine rebuild costs $10,000 - $15,000 and puts you out of work for a week or three, you don't mind paying a bit more for your oil. The C certification tests have been largely developed by Mack, Caterpillar, and Cummins to provide the additives necessary to keep these engines running a long time. The latest commercial certification is CI-4, which includes extra protection for high temperature high revving motors. Since it's designed for diesel motors, they don't care about no stinkin' catalytic thingys, and CAFE is a place where you get a cup of joe and a donut.

The C certified oils are all also S certified, just as some S certified oils are also C certified. The best C certified oils are SH, sometimes SJ. I don't know of a C certified oil which is SL. The best S certified oils are CF, which is a relatively old C standard, and does not include the tests for high speed high temperature engines that CG, CH, and CI have. In fact, CF oil does not meet the current factory standards for Volkswagen or Mercedes diesel passenger cars.

The API charges serious money to test an oil and certify it. If the API really tested the oil in their independent lab, and the oil company pays their royalties on time, the oil company gets to display the API seal on their product. Some smaller companies don't pay the API to test their oils and certify them. In these cases, you won't see the API seal, instead you'll see some words like "Meets or exceeds all manufacturers warranty requirements. API Service SJ, SL, CF." It's up to you to decide if you trust this manufacturer to actually test their oil themselves and tell you the truth about the results.

Another institute that certifies oils is called the Japanese Automotive Standards Organization, JASO. One wonders why this Japanese organization has an English name. . . In any case, they have two classifications for motorcycles, "MA" and "MB." MA is the one you want. MB is like the API SL category, it's got all those nasty friction reducing chemicals that may scare your clutch into misbehaving. Again, there is an official JASO seal if the oil has been independently tested. The seal is a rectangle; in the upper quarter of the rectangle will be a serial number, and the lower three quarters will just have the letters MA. If the oil manufacturer did their own testing, instead you'll see just words like "Meets or exceeds JASO MA standards."

Some manufacturers also sell something they call "racing oil." Normally, this is actually fairly decent oil, but you should not be mislead into thinking racing cars use the best oils for you. Race drivers start their engine one time only, warm it up slowly and carefully, then run the engine near or at the red line for a couple hours. 100 to 500 miles later, they completely tear down the engine and replace all the worn parts, the oil, and the oil filter. If you think you might like to go more than 500 miles between major engine rebuilds, you might consider that your use of your engine is quite different from Michael Andretti's.

Why do we change our oil?
We're now in a position to discuss this. Your oil is a combination of one or more base oils and a complicated additive package. The base oils will actually last as long as your motorcycle - many hundreds of thousands of miles, several years. The reason we change our oil is the additive package wears out. The buffers get used up neutralizing acids. The detergents and dispersants get used up clinging to gunk that's too small for your oil filter to pick out. The VII package gets shreaded by your transmission. You could imagine a device that pulled out your oil, gave it a very thorough cleaning, replaced the buffers, detergents, and VII molecules, and put it back into your engine. Sort of a motor oil dialysis machine. However, in a country that has Texas and Alaska, in a world where oil is $30 / barrel, this makes no sense. So, we dump out our entire four quarts of oil because 3% of the oil is used up. It's really just a cheap way of getting a bunch of contaminants out of our engine. This is why it does make sense to recycle oil: if you can process the oil hundreds of gallons at a time, you can separate out the base stocks economically. If you use synthetic oils and bring your used oil to a recycling collection point, you can feel especially good: a bunch of school buses and city buses are going to get an extra little kick in their base oil because of you. In fact, you can tell your wife that's why you need this exotic, expensive synthetic oil: it's solely out of your concern for the children. If everybody used Spiffo-Magic SuperLube the recycled oil would be junk, and in no time flat the school buses would all break down and the kids would have to walk to school, 23 miles, in the snow, uphill both ways. Why, in no time flat the kids would lose weight, improve their cardiovascular conditioning, and just generally be more healthy and have more energy. What a nightmare!

Choosing an Oil for Your Motorcycle
There are a few special problem areas for motorcycle oil.

Most motorcycles have wet clutches, which means the motor oil runs through the clutch. If the motor oil has too much molybdenum in it, there are fears that the clutch can start slipping. No one I know has ever actually had this happen to them, but the warnings are all over your owners' manual and the oil companies' web pages. On the back of all certified oil cans is a circular stamp with the certification. Avoid oils that say "energy conserving" in the bottom half of the donut. These oils contain friction modifier additives that could cause clutch slipping over time. Essentially all 10w-30 oils are energy conserving, and should not be used in your motorcycle.
Most motorcycles run the engine oil through the transmission, and the transmission gears are very hard on the oil's VII package. This means that over a couple thousand miles, the oil's viscosity can break down. Standard car oils are only good for typically 2500 miles before they've lost about half of their viscosity. Remember, 10w-40 oils contain a lot of VIIs which tend to shear in your transmission, so I believe 10w-40 oils should be avoided. You can't use 10w-30 because of the friction modifiers. This doesn't leave much. Commercial 15w-40 oils are a good choice, because they have relatively few VIIs which are the more expensive shear-stable sort. Synthetics typically don't contain much of a VII package, so shear is not as big an issue with them.
AMSOil and Golden Spectro are JASO-MA certified. Some people consider this important. Interestingly, although Honda recommends a JASO-MA oil, Honda oil is not JASO-MA certified. Mostly JASO-MA is pretty much equivalent to SH. Personally, I don't care about JASO standards.
Some people use their motorcycles only sporadically. This means the oil can all drain completely into the sump, leaving no protective film on the bearings. The first start after a long period of non-use can be particularly hard on an engine.
Finally, air-cooled motorcycles tend to run rather hot, and all motorcycles these days are made to extremely tight tolerances. This is a problem for oils with a low flash point - they can burn off into ash. Over 25,000 miles or so, this ash can build up in your engine to the point where small oil passages are clogged. This is not a theory, it happened to me once. Again, this points towards synthetic oils, which have much higher flash points.
There are several key advantages to using Synthetic Oils:

Synthetic oils have a higher viscosity index than mineral base oils. Synthetics have better resistance to thinning at high temperatures and thickening at low temperatures.
Since synthetics have little or no VIIs, synthetics last longer in service without radical changes in viscosity.
Synthetics have a much higher film strength than petroleum oils, so it take a lot longer for the oil to drain completely off your bearings and into your sump.
Heat is a major cause of lubricating oils failing while in service. Mineral oils begin to fail at 250F. Synthetic oils can handle 400F of continuous heat caused by friction and combustion.
Synthetics have better thermal stability and oxidation stability than most highly refined mineral base oils with inhibitor additives.
Synthetics have very low volatility compared to mineral base oils. Synthetics don't tend to burn off.
Synthetics possess unusual solvent power for dissolving gasoline and diesel fuel residues which enter the crankcase as contaminant byproducts from combustion.
Recommendations
The question of which oil is best is not settled. We know what we want: the oil is inexpensive, lasts a long time, and makes our engine never break. No magazine ever tests oils for 100,000 miles to see which causes the least engine wear. There are various articles in MCN which do a chemical analysis and make recommendations based on the content of the additive package. I am very skeptical of this, as the utility of these chemicals at various levels is never tested, and the base oils are not tested. There are a couple articles that actually test for viscosity breakdown, and standard petroleum oils don't do very well. If you're using a standard automotive petroleum oil and running it for more than 3,000 miles, you are taking your chances. By 3,000 miles, the VII additives are pretty much all broken down, and the oil has therefore thinned out enormously.

Some people should, in my opinion, clearly use a synthetic oil. You should be using a synthetic if you routinely start your engine in temperatures under 40f, 5c. You should use a synthetic if you leave your motorcycle sit unused for months at a time. You should use a synthetic if you are unable or unwilling to change your oil within 3000 miles. If you have one of these new 4-stroke MX bikes you should be running a synthetic. Some of these MX bikes hold only one quart of oil, all of them have marginal cooling systems, and if there's a more severe use of an engine than MX, I don't want to be physically present when it happens.

It seems pretty clear that if you change your oil every 2500 miles or so and never miss, you can use pretty much anything. If you want to go the full Honda 8,000 mile recommended service life or more, I believe you must use a synthetic. It would be nice to have hard evidence on the viscosity and acidity of different oils as they are run for many miles, but at this time almost no such evidence exists. Current measuring devices cost about $1500 for the portable versions, or you could send samples of your oil off to a lab at about $50 per sample. Perhaps sometime someone will produce a relatively inexpensive portable instrument, then we could change our oil when it was used up instead of relying on some kind of educated guess from averaged data.

Two synthetics stand out from the rest: Mobil Delvac 1 and Shell Rotella T Synthetic. These are C certified industrial oils meant to be purchased in 55 gallon drums and used by companies which run a lot of diesel engines. The Commercial oils, as discussed above, have more expensive additive packages which are meant to prolong engine life and oil life, as opposed to being cheap to buy at Pep Boys and helping the car companies meet their CAFE requirements. These oils meet all the automobile requirements through SJ, and also have extra additives to help pick up gunk in the engine, to keep the oil from becoming acidic, and to maintain the oil's viscosity over a long time. In fact, the manufacturers talk about their oil's viscosity resistance to shear forces - exactly what a motorcycle needs. Shell Rotella-T Synthetic is available at Wal-Mart for $13 / gallon, so I consider this the motor oil of choice. Delvac-1 is very hard to get in the west - there are only two places in all of California where you can buy it. When used with the correct filters, these oils are certified for 50,000 mile oil change intervals, and are frequently used for 100,000 to 150,000 miles in diesel long-haul trucks. Now, before you get all excited about the possibilities, you must also keep in mind that the diesel engines don't run their oil through their transmission, and the large diesels all have two oil filters, one a normal paper filter, and the other a 1 or 2 micron filter that catches pretty much everything. We don't have these secondary ultra-fine oil filters on our bikes. Also, the large diesel engines hold eleven gallons of oil - a oil and filter change costs these guys $350 if they use synthetics, $150 if they don't.

The synthetic diesel oils are 5w-40 oils. Some people have expressed concern to me that this doesn't match the 10w-40 specification for their engine. The 5w rating only applies when the oil is cold, below about 80 f. Once your oil and engine are up to operating temperature, these are 40 weight oils, just like all the others. In cold conditions, under 40 f, the 5w oils are much better for your engine than a 10w oil.

AMSOil, Motul, Mobil-1 MX4T and Golden Spectro are apparently made with high quality additive packages, similar to the commercial synthetics. Personally, I would find it reassuring if these oils were CI-4 certified. However, many motorcyclists have used these oils for years with good results. They are all fine oils, and perfectly acceptable to run in your motorcycle.They are a bit on the pricey side. AMSOil and Motul synthetics contain no petroleum oils - they're pure synthetic. To the best of my knowledge, all other synthetic oils contain some amount of Group III oil.

Mobil-1 Red Cap is a fine oil. It does not have the commercial additive package that Delvac-1 has, so I don't consider it as good an oil, but it's a perfectly acceptable oil to use in your bike. The Green, Blue, and Black Cap Mobil-1 oils are all energy conserving, and should not be used in your motorcycle.

If you live in another country, you'll have to do a bit of research to decide on an oil. Generally, any oil certified for use in a late model Volkswagon or Mercedes turbo diesel is a good choice. Another good idea is to go to a truck stop and ask the truckers about brands. Rotella is marketed all over the world, but in other countries it's called Rotella or Rimola or Helix Ultra, and the formulation may be a bit different, depending on local climate and preferences. It will likely also be a lot more expensive than it is here.

If you prefer a less expensive petroleum oil, Chevron Delo 400, Mobil Delvac 1300, and Shell Rotella T are available at any auto parts store for under $7 per gallon. This price is reasonably competitive with passenger car oils, and you are getting a Group II oil with the superior commercial additive packages. I don't have any information about how long you can run these oils before their viscosity breaks down, but I'm confident it's at least as long as the best consumer petroleum oil. If you're really into saving money, you can often find these oils locally in 10 gallon drums for about $50. This should keep your bike, your car, and your wife's car in good shape for at least a year. Farmers, ranchers and truckers buy these oils in large quantities, and we get to ride piggy-back on their economies of scale.

If you want to do some research on oils yourself, here are some links. I read all this stuff and I'm still alive, but a bit weird. Oil viscosity defined. API Service classifications. Everything you ever wanted to know about oil, but were afraid to ask. Here's what an additive package manufacturer has to say about oils. Lubricants primer by Red Line. All about oil by Ed Hackett, a college professor. Oil Advice from Mike Guillory, a petroleum engineer. More Oil Advice. Jeff Di Carlo also has an opinion. Check out the articles in MCN Jan-Feb '03. MCN '94 includes viscosity breakdown testing. The history of synthetic oils, only *slightly* self- serving. Oil additives = snake oil? (yes)

Mobil wants your money, as does Shell, Valvoline, AMSOil and Spectro Oil. You may be skeptical about the oil companies interests, but they are the people making what we buy so it's interesting to hear who they think we are and what they think we need.