Dear Tom and Ray:

My question is about different brands of oil. Should you stick with the same brand every time you change the oil in your car? Does it harm the car at all to switch brands, as long as they are the same viscosity? One new-car dealer tells me to use his brand every time or the engine warranty won't be any good. This sounds ridiculous to me, but he's got me wondering. -- Mitch

Tom: And people wonder why nobody trusts car dealers.

Ray: You're absolutely right, Mitch. That's complete bull droppings. You can use any brand you want and mix them together as much as you want, and it will have no effect on your warranty. All of the major brands of oil are substantially the same.

Tom: There are two things to look for. The American Petroleum Institute (API) rates oils for a variety of properties. Those that meet the most recent standards are currently labeled "SJ."

Ray: "SH" and "SI" are recent vintages, too, and they're fine for all but the newest cars. So look for those API ratings.

Tom: The other thing to look for, as you say, is the proper viscosity. Check your owner's manual and see what your car calls for. Most call for 5W30- or 10W30-weight oil. But some recommend specific viscosities for unusual conditions or temperatures.

Ray: Other than that, your only really important consideration is whether you like the colors on the label.

Wait! Don't buy another car without the mechanic's checklist that's included in Tom and Ray's pamphlet "How to Buy a Great Used Car: Secrets Only Your Mechanic Knows." It will help you get a good used car and avoid the clunkers. To order, send (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475. You can also order online.

© 1998 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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