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Motorcycle vs Car Oil


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An ongoing argument forever about whether the use of automotive formulated oils will adversely affect the operation of a motorcyle’s systems can be finalized with the following determinations.

1.) The wet clutch in a motorcycle works on the principle of friction.

2.) There is threshold amount of friction required to properly transmit the power produced by the engine to the output sprocket. When the amount of friction goes below that threshold the clutch slips.

3.) The engineers do not characteristically design any more than 15 to 20 percent more load-carrying capacity than needed into a clutch system for economic (it costs more for more plates) and/or ergonomic (the clutch lever is too hard to pull) reasons. These clutch systems are designed with a motorcycle graded lubricant as the specification. To reduce the inertial resistance the diameter and surface area of the clutches has been reduced, especially in the high-output sportbikes.

4.) The new automotive oils claim reductions in friction of up to 15%.

5.) Do the math.

6.) The above principles apply to EVERY wet clutch system.

7.) The above principles also apply to sprag-type starter system used on 95% of all motorcycles today, the only notable exception being Harley-Davidsons.

We sell motorcycle-graded oils for this reason. The relatively low production volume of these products causes the price to be higher, sometimes a hell of a lot higher. However when taken in context of the added expense per mile it isn’t really that much more, especially if a $250 clutch repair is avoided.

I like the old HD primary oil. You know that HD can't badmouth that if there is a problem.

Do NOT use car oil in your motorcycle.. You will NOT save money by putting automotive oil in your motorcycle.. While many people have done just that for many years, it is crazy to do it today.. Research has enabled the oil companies to develop motorcycle oils (Spectro, Belray, Kendall etc) that last 2500 to 3000 miles or more in a motorcycle engine. If you use automotive oil in your motorcycle the polymers in that type of oil will be broken down within 800-900 miles..
Automotive oils are NOT designed for use in air-cooled engines.. If you insist on using an automotive type oil in your motorcycle, you may loosen up debris in the sludge trap that debris may ruin the rod bearing when it starts circulating through the oiling system.

Although, you won't notice the difference right away, Running worn-out oil will lead to earlier deterioration of vital engine components. The money you think you are saving on cheap oil will end up being spent, plus some on engine service and replacement parts