Originally posted by FastFordFreak: It can cause leaks in high-mileage engines
WRONG! Synthetic oil is NOT the cause of oil leak. It's because of other problem like the gaskets are already getting brittle, and the more refined synthetic oil can seep through the cracks. The only bad thing about synthetic oil is cost.
Not wrong, actually.
Post-conversion leaks often are revealed due to the aggressive detergent packages found in hi-end synthetics. If the engine is oil-fouled due to age or neglect, the synth will very quickly clean out the residual gunk deposited by conventional oils. This can reveal existing leaks or weaknesses that had been masked by the gunk.
Actually, Airknight said it will not CAUSE leaks. As you said it may REVEAL problems that already exist.
