Dear Tom and Ray:

Does it harm an automatic transmission if the fluid is well above the "full" mark on the dipstick? Lynn

Tom: Apparently it does. You may notice a little warning that says something like "Caution: Do Not Overfill. Overfilling May Lead to You Making Your Mechanic's Boat Payment This Month."

Ray: But I have to admit, I've never personally seen a case where overfilling has caused any damage to an automatic transmission. I've just seen the extra fluid leak out.

Tom: I suppose what can happen is that the oil can foam and "froth," kind of like a root beer float. And if it's foamy, the fluid won't be able to adequately lubricate the transmission, and it gets damaged.

Ray: But this only a theory. We've never actually seen any evidence of this occurring. So in the interests of science, I'm conducting a little experiment as we speak. On my way home last night, I stopped and put a quart of IBC Root Beer in my brother's transmission. And I guess we'll see what happens.

How can you tell if a used car is in good condition -- or even OK, for that matter? Find out by ordering Tom and Ray's pamphlet "How to Buy a Great Used Car: Things That Detroit and Tokyo Don't Want You to Know." Send $3 and a stamped (55 cents), self-addressed, No. 10 envelope to Used Car, PO Box 536475, Orlando, FL 32853-6475.

© 1995 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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