One question that invariably arises when deciding on which oil to use in your motorcycle is whether to use synthetic oil or petroleum oil. Although the answer lies in what your expectations are for your motorcycle, here are a few issues you should consider when making your choice:
HIGH TEMPERATURE PERFORMANCE
I believe this is generally a well known fact, but synthetic oils will, in general, perform much better in high temperature applications than petroleum oils will.
The synthetic basestocks that synthetic oils are manufactured from have much higher flash points than petroleum oils typically do.
In layman's terms, the flash point of an oil is the point at which it begins to
vaporize. The higher this flash point, the better the oil will hold up in high temperature environments.
In addition, because synthetic oils are made up of particles of uniform size, they have less "internal friction" than petroleum oils (which are made up of particles varying greatly in size). This lowers the temperature of the oil, thus improving the cooling qualities of the oil. Of course, the end result is cooler engine temperatures.
Secondarily, synthetic oils do not cause the "blanket effect" that petroleum oils do. Because petroleum oils are made up of particles of varying sizes, the smaller particles tend to flow freely through the center of the oil galleries within your engine while the larger sized particles will be pushed to the "outside" of the oil stream - next to engine components. These large particles, for the most part, remain there and do not distribute heat from engine components back to the oil.
The uniform particles within a synthetic oil will all flow just as easily through oil galleries. Larger particles are not present to "blanket" engine component surfaces. Therefore, heat is distributed into the oil and carried away.
The end result is that a good quality synthetic oil can lower engine temperatures by as much as 20 to 50 degrees F. That can significantly extend the life of critical engine components. In addition, less stress is put on the oil, which extends its useful life as well.
SYNTHETIC VS. PETROLEUM OIL
Of course, the harder you run your bike, the more important these issues will be. Leisure riders will not have as much problem with this issue, but the issue does still exist.
More to come, watch this space