The operating conditions of a typical motorcycle are considerably different than those of a typical passenger car and thus require an oil capable of handling the unique demands. One primary difference, wet clutch lubrication, is already addressed by the current JASO four-stroke motorcycle engine oil specification (JASO T 903:2011). Another challenge for the oil is gear box lubrication, which may be addressed in part with the addition of a gear protection test in a future revision to the JASO specification. A third major difference between a motorcycle oil and passenger car oil is the more severe conditions an oil is subjected to within a motorcycle engine, due to higher temperatures, engine speeds and power densities.
Scooters, utilizing a transmission not lubricated by the crankcase oil, also place higher demands on an engine oil, once again due to higher temperatures, engine speeds and power densities. However, because scooter oils do not need to lubricate a wet clutch or protect gears, scooter oils can provide more fuel economy benefits than motorcycle oils, when properly formulated.
First, this study compares the piston deposit performance of motorcycle oils and passenger car oils in the API Sequence III Test and in a fired-engine motorcycle piston deposit evaluation. While the API Sequence III Test is certainly an effective tool for ensuring passenger car motor oil piston deposit performance, the results show that some oils formulated to meet the performance requirements of the Sequence III test do not match the performance of motorcycle-specific oils in a motorcycle piston deposit evaluation.
Second, this study compares the performance of different oils in the JASO clutch friction test (SAE#2) and in a fired-engine Scooter Fuel Economy Test. The results indicate that JASO MB performance, as determined by the SAE#2 clutch friction test, is not necessarily a predictor of real fuel economy benefit.
