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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 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. 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 0w-20, 5w-30 and 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 1500 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.

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. Film strength is very important if you're a sporadic rider.

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 takes a lot longer for the oil to drain completely off your bearings and into your sump.

Diester synthetics are polar molecules with solvent properties which dissolve residues and combustion byproducts.

Choosing a Break-In Oil for Your Motorcycle

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.