Synthetic motor oils

Q: Greg, I’ve been unable to find any information that compares synthetic motor oils to regular, petroleum-based motor oils. I feel that the synthetic motor oils are much better because they can go longer between oil changes, but I can’t find any real data to confirm this. — David H., Rocky Mount, N.C.

A: David, the synthetic oils on the market today are superior to petroleum-based oils for several reasons. However, the drain-interval (oil change) data might surprise you. Synthetic oils can withstand much greater engine temperatures before a breakdown in lubricating ability. They also have better friction-fighting properties, which allow better protection in cold weather, too. Synthetics don’t offer any advantages in extended use over conventional oil.