Oil

Oil is a controversial topic. On the forums, many an argument has been had.

Almost the entire page is based on a fantastic reference[2] giving you the big picture and the details… And yes, this is the abridged version. For a lot more history and details, go to the linked article. If you don't like reading and researching as much as I do, just use the Table of Contents below to pick and choose which topics are relevant. The super short version seems to be:

  • High quality dino oils can be just as good as synthetics, but break down faster because they require more additives.
  • The smaller the ratio between the cold and hot "weights", the less additives needed, the better—thus, 10w40 is 1:4, and would be degrade faster than 20w50, which is 1:2.5. So, 20w50 > 10w40.
  • Diesel engine oils are made to last, Consumer automotive oils are made to meet ever tightening EPA requirements. Guess which is better for your engine?
  • Modern car oils (since SH became obsolete in the 90's) have friction modifiers that screw with wet clutches.
  • Most modern "Synthetic" oils are actually mostly modern, highly refined [group III] dino oils. There was a lawsuit about it, but it held up.
  • The only pure synthetics? "To the best of my knowledge, Delvac-1, AMSOil, Redline, and Motul 5100 are the only oils made from pure traditional synthetics."
  • The ONLY thing he says about synthetics causing problems in wet clutch bikes, is one sentence at the very end:

Mobil-1 automotive oils all contain small amounts of moly - about 100 to 200 ppm. This can cause clutch slippage in some motorcycles. I've only heard of this being a problem in Honda Shadows.

Earlier, he also mentions:

It's simply not the case that synthetic oils are more "slippery" than conventional oils.

What follows is the abridged article, unless noted otherwise.

FJ specific specs:

Engine/transmission oil:
Type API Grade SE or SF
Viscosity:
Up to 15°C (60°F): SAE 10W30
Above 5°C (40°F): SAE 20W40
Capacity:
With Filter change: 3.35 liters (3.5 US qt, 5.9 Imp pts)
Oil change only: 3.0 liters (3.2 US qt, 5.3 Imp pts)

Understanding common terms:

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.

What difference is there between Synth and non-synth?

Group III oils [editor: highest grade of dino oil] have properties approaching or equaling 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-cooled, 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 and other additives.

Since about 2000, it has become possible at moderate extra cost to process Group II and Group III oils so that their performance below 32° nearly matches the performance of traditional synthetics. Because of this, the oil companies found they could now produce relatively inexpensive 5w-30 and 0w-20 oils. Car companies were quick to see that such oils would help reduce the fuel consumption of their vehicles by a percent or so, which is important as Detroit finds themselves selling more trucks than cars. So, these "fuel-efficient" oils are quickly becoming the factory recommendation in most cars. It's not at all clear that these new low- viscosity oils lead to the longest engine life, but it is clear that these oils help the car companies meet their CAFE federally- mandated fuel economy standards.

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. The much more expensive traditional synthetics are now available in their pure forms only in more expensive and harder to obtain oils. To the best of my knowledge, Delvac-1, AMSOil, Redline, and Motul 5100 are the only oils made from pure traditional synthetics.

Semi-synthetics

"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. The manufacturers love this stuff: it costs about 15% more to make the oil, and they get to charge about double. I don't recommend semi-synthetics. Save your money and take your kids to McDonalds.

How Single-grade oils work

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.

How multi-grade oils work

An oil sold as 10w-40 is no thicker than 10 weight oil under Winter (10w) conditions, meaning below freezing. 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 or below 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 or the hydraulic valves in a diesel engine. 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.

One way to judge the VII content of your oil is to read the VI, the Viscosity Index, at the manufacturer's web page. The base oils all have similar VIs to start with, so generally speaking, the higher the VI in the blended oil, the more VIIs are present, and the less suitable the oil is for motorcycle usage. John Evans did just such a survey of Valvoline, Chevron, Exxon, Quaker State, Citgo, and Conoco oils. He found that the 5w-30 oils all had VI's in the range of 158-162; the 5w-20 oils had VIs of 148-154; the 10w-40 oils had VIs of 147 to 150; 10w-30 oils had VIs of 134 to 139; and 20w-50 oils had VIs of 120 to 125.

Motorcycle vs Car: Which is harder on oil? READ

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 equivalent. By contrast, Dr. Woolum tested a petroleum oil in his Honda Accord. After 3600 miles, the 10w-40 oil was 10w-37 equivalent. Motorcycles are indeed significantly harder on their oils than cars. Based on this result and the VI numbers above, it would seem that 10w-40, 5w-20, and 5w-30 oils cannot be safely used in motorcycles for more than 1,000 to 1,500 miles.

Gear oil vs. Motor oil

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.

Additives: What are they, and what they do

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 will 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. Oil companies are cutting back on zinc and phosphorous, as these metals are hard on your catalytic converters. They're substituting molybdenum disulfide, which lowers friction and improves gas mileage. It also causes problems for people with wet clutches, that is most motorcycles.
-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.

Why Use Diesel-Engine Grade Oil?

The additive packages 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. 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, Detroit and Cummins to provide the additives necessary to keep these engines running a long time. The latest commercial certification is CI-4 Plus, 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 thingies, and CAFE is a place where you get a cup of joe and a donut. CI-4 Plus differs from CI-4 with higher detergent requirements and better sheer stability. The shear stability is exactly what motorcycles need due to running the engine oil through the transmission.

Although C standards are changed every few years, the older standards are enhanced, not superceded. So, newer higher rated C oils are simply better than older lower rated oils.

Although few car owners test their oil regularly, most large trucking companies routinely do oil analysis on their diesel trucks. Used oils are checked for viscosity breakdown, for detergent and dispersant function, and for metal contamination that would indicate engine wear. C oils that don't measure up are quickly run off the market place. To prevent engine wear, the best strategy is to keep deposits off the pistons, rings, and bearings. Therefore, diesel oils typically contain half again more detergents, double the dispersants, and a much more expensive and robust VII package than S type oils. If you go to an auto parts store, convenience store, or grocery store, you'll see that there are dozens of brands of automotive oils, all claiming to be the best. If you look at truck stops, you'll see there are only a very few diesel oils sold, typically Rotella, Delo, and Delvac. Trucking companies find what works for them and won't switch. They're not interested in saving a dollar a gallon on some unknown oil.

Why change oil/Why recycle oil?

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 shredded 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.

"Break-in" oil

The theory that synthetic oils should not be used during break in is the same as the theory that your engine will break in better if you use synthetic oil but add a dinner candle to your four quarts of engine oil. Frankly, I find this theory, um, questionable. Oh, hell, laughable. Corvettes and Porsches come from the factory with Mobil-1 in their engines. Remember, these engineers have designed world-champion engines for F1, Indy, Le Mans 24 hours, etc.

There's a lot of mythology surrounding break-in oil. It's simply not the case that synthetic oils are more "slippery" than conventional oils. Also, break-in of a modern engine is completely different than break-in of an engine made before about 1980. Modern engines, by comparison to something made in the '60s, are pretty much already broken in from the factory due to the fact that today we hold much tighter machining tolerances. The exception, of course, would be the Ural, a motorcycle made on a production line unmodified since about 1935.

I recommend you change your break-in oil at 75 to 100 miles, 100 to 150 kilometers. Your engine does shed a fair amount of metal particles in the first 20-50 miles, and I really can't understand why you would want this stuff floating around your bearings for the first 600 miles, 1000 kilometers.

I put Shell Rotella "synthetic" (87% group III) oil in my DL650 at 75 miles. It burns no oil, gets great gas mileage, and runs great. I recommend you switch to a good synthetic at your first oil change.

Mixing Different Oils

I'm sometimes asked if it's ok to blend your own oils. Yes, it is. Oils are all made out of pretty much the same chemicals, and nothing really bad will happen. If I wanted to blend my own oil, I expect I would use something like 25% Motul 5100 10W-40 and 75% Chevron Delo 15w-40, which would get me both the advantages of a lot of diester stock (5100 is pure diester) and the diesel additive package. In the winter, however, I would use 25% Motul and 75% Rotella synthetic, to get the superior low temperature performance. In fact, I just run Rotella synthetic in everything I own, year round: ST1300, DL650, Superhawk, Chevy Silverado, motorhome.

International Oil Choices

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. Sorry. I don't make your tax policy. Nor ours. They would all be very different if I did.

If You're a Cheap-O

Base oils made with the Iso-DeWaxing process 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 Group-II base oils leave far fewer wax and tar deposits in your engine, and have much better low and high temperature performance than Group I oils. The resulting oils are roughly 97% good stuff (oil) and 3% bad stuff (paraffin and wax). We just cut that 12" dinner candle down to about 2½".

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 [editor: back in '04, I guess?], or at Sam's Club or Costco for under $6 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. Notice in the table above that these oils have particularly good high shear film strength, meaning the protection you get for your bearings is much better than with a 10w-30 or 10w-40 oil. 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.

Oil Additives

The GSResources featured an article that went over the four major types of oil additives, and examined their claims[3]. The conclusion is, essentially, the following:

… For example: Avco Lycoming, a major manufacturer of aircraft engines, states, "We have tried every additive we could find on the market, and they are all worthless."

Briggs and Stratton, renowned builders of some of the most durable engines in the world, says in their report on engine oil additives, "They do not appear to offer any benefits." North Dakota State University conducted tests on oil additives and said in their report, "The theory sounds good - the only problem is that the products simply don't work." And finally, Ed Hackett, chemist at the University of Nevada Desert Research Center, says, "Oil additives should not be used. The oil companies have gone to great lengths to develop an additive pack age that meets the vehicle's requirements. If you add anything to this oil you may upset the balance and prevent the oil from performing to specification." Petrolon, Inc., of Houston, Texas, makers of Petrolon and producers of at least a dozen other lubrication products containing PTFE, includingSlick 50 and Slick 30 Motorcycle Formula, claim that, "Multiple tests by independent laboratories have shown that when properly applied to an automotive engine, Slick 50 Engine Formula reduces wear on engine parts.

Test results have shown that Slick 50 treated engines sustained 50 percent less wear than test engines run with premium motor oil alone." Sounds pretty convincing, doesn't it? The problem is, Petrolon and the other oil additive companies that claim "scientific evidence" from "independent laboratories," all refuse to identify the laboratories that conducted the tests or the criteria under which the tests were conducted. They claim they are "contractually bound" by the laboratories to not reveal their identities.

In addition, the claim of "50 percent less wear" has never been proven on anything approaching a long-term basis. Typical examples used to support the additive makers' claims involve engines run from 100 to 200 hours after treatment, during which time the amount of wear particles in the oil decreased. While this has proven to be true in some cases, it has also been proven that after 400 to 500 hours of running the test engines invariably reverted to producing just as many wear particles as before treatment, and in some cases, even more. No matter what the additive makers would like you to believe, nothing has been proven to stop normal engine wear. You will note that all of the research facilities quoted in this article are clearly identified. They have no problem with making their findings public. You will also note that virtually all of their findings about oil additives are negative. That's not because we wanted to give a biased report against oil additives - it's because we couldn't find a single laboratory, engine manufacturer or independent research facility who would make a public claim, with their name attached to it, that any of the additives were actually beneficial to an engine. The conclusion seems inescapable.

API grades

A clarification on oil API grades in relation to wet-cluch bikes[1]:

Over the years, the API has improved and changed these standards. The most current S standards are SL and SM. 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. SL and SM oils are both low phosphorus; SM oils which are labeled "energy conserving" are high molybdenum.

About every three years or so, the API releases a new S standard. The new standard supercedes the old standard, so, for example, the SH standard included extra high temperature deposit protection due to the popularity of turbo engines in the early '90s; SJ oils did not have this high temperature protection, as that portion of the standard was dropped. This means that for some cars, oils made to the older rating systems are sometimes better than oils made to the new standards. SH certified oils are probably the best of the S oils for motorcycles and high- performance sports cars, but you pretty much can't buy them anymore. Oils which are labeled "energy conserving" are bad for any vehicle with a wet clutch, meaning most motorcycles. Essentially all 0w-20, 5w-30, and 10w-30 oils are energy conserving and should not be used in your bike.

Most people blending S type automotive oils are buying their base oils from a company who is most likely using the Chevron Iso- DeWaxing process to make their oils, then buying their additive package from another company that is highly constrained by the API standards. The cost of getting an API certification for a single S motor oil formulation is from $125,000 to $300,000. The cost for C certification is $275,000 to $500,000. Once testing is complete, the oil can be licensed for $825 per year, plus a small royalty fee per gallon sold for all gallons over one million. The length of time between new specifications is now approximately 2 to 3 years, which does not allow a great deal of time to recover testing costs.

Additive companies, such as Lubrizol, Ethyl, Infinium and Oronite develop licensed additive formulas that they offer to oil companies to re-license. It is inexpensive to re-license one of these formulas, and the majority of oil companies choose to do this to avoid the costs associated with testing. Thus, the same chemistry is being sold under many brand names. Because of this, S type automotive oils have pretty much turned into a commodity. Although the people selling a particular brand may wish you to believe their oil is superior to any other, in fact if it's got the API seal on it, it's probably about the same as any other similarly rated automotive oil.

Conclusion

I get a lot of email, "My buddy has 283,000 miles on his Yamazuki 867 Nintruder, and he's never used anything but 35¢ per quart grocery store oil changed every 48,000 miles." Here's the truth: modern Japanese engines are amazingly well engineered and can tolerate a surprising amount of abuse. However, putting automotive oils in your motorcycle and running them for more than 1500 miles is abuse. I abuse my motorcycle enough with the way I ride them without adding on the abuse of using cheap oil that will break down in 1500 miles.

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. 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. … Consumer Reports once did a 4,500,000 mile test of oils in NYC taxicabs, however these engines only start once per day and are water-cooled, so they mostly avoid cold start-ups and overheating. If you're using a standard automotive petroleum oil in your motorcycle and running it for more than 1,500 miles, you are taking your chances. By 1,500 miles, the VII additives are pretty much all broken down, and the oil has therefore thinned out enormously.

Your engine will not explode if you use Spiffo-Magic Superlube for 4,000 miles. Your engine will not explode if you never use synthetic oils. However, any of these choices puts additional strain on your engine. You buy $65 tires for your car that last 45,000 miles, and $100 tires for your bike that last 8,000 miles. Why on earth would you try to save $5 on each oil change to buy an oil that can't hold up in a motorcycle engine? My DL650 runs its oil through the transmission, I run off-road (extreme environment due to silicon blow-by at the piston rings), I'm pretty much always revving my engine at 5500 rpm or more (red line on the Corvette, the one that comes with Mobil-1 as factory fill). I stress my little engine enough without making it use dinner candles as lubricants. Nor do I wish to make the bearings run in 10w-40 oil that's broken down to 10w-15 oil.

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 40°f, 5°c.
  • you live somewhere where it gets below -35 degrees, and you want to start your car. In this case you must use either Mobil-1 0w-30 or the Canadian 0w-40 Rotella. If you're riding your bike in -40 degrees, I want a picture just before you die.
  • you leave your vehicle sit unused for months at a time.
  • you are unable or unwilling to change your oil within 2000 miles.
  • you have one of these new 4-stroke MX bikes. These MX bikes hold only about 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.

If it's below -55c, -65f, stay home. Really.

Three synthetics stand out from the rest: Mobil Delvac 1, Mobil-1 SUV 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.

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 5100, Mobil-1 MX4T, Mobil-1, Redline, 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. Delvac-1, AMSOil, Redline 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 automotive oils all contain small amounts of moly - about 100 to 200 ppm. This can cause clutch slippage in some motorcycles. I've only heard of this being a problem in Honda Shadows.

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