I have heard thatSynthetic oils can't be used in roller bearing applications because synthetic oil is too slippery. Because of this, the rollers bearings tend to slide rather than roll which leads to accelerated wear of the rollers.
No!. The exact opposite it true. The chopping action of the roller bearings causes the failure of the viscosity improver additives found in petroleum oils, not high-quality synthetics. For example, a 10w-40 petroleum oil might sheer back to something like a 5w-10. This loss of viscosity results in breakdown of film strength. When this happens, there can be metal-to-metal contact of the surfaces of the roller and crankshaft(or camshaft) inside the engine which results in scuffing damage of these parts.
In fact many Harley Davidson dealership technicians for years up until recently have been are telling customers that synthetic motor oil is "too slippery" and can cause flat spots on roller bearings because the bearings won't turn. Now Harley Davidson recommends synthetic’s!
