I had a full tank of gas, but put in a bottle of transmission fluid by mistake.

Dear Car Talk

Dear Car Talk | Oct 01, 1994

Dear Tom and Ray:

I have made a terrible mistake. I keep my dry gas in one spot on my cellar shelf. Somehow, a bottle of transmission fluid was put there by accident. You guessed it. I had a full tank of gas, and put in a bottle of transmission fluid by mistake. Since then, I have added a bottle of dry gas every three fill-ups, and kept the tank full with premium gas. So far, I have travelled over 200 miles, and it's still going. What damage am I doing? It's a 1985 Dodge.

TOM: You're not doing any damage, Yvonne. Don't worry about it.

RAY: First of all, it's important to know that automatic transmission fluid (ATF) is basically an oil. And we all know it's not that harmful for engines to burn oil, because every car my brother's ever owned has burned oil.

TOM: And in fact, back in the old days, people used to put stuff like ATF and "mystery oil" (which bore a striking resemblence to ATF) into their gas tanks ON PURPOSE, because they believed these oils had cleaning properties. They were said to remove deposits and varnishes from the engine's valve train.

RAY: We don't generally recommend that anymore because there are now detergents in gasolines that do a better job of keeping the engine clean. But one bottle of ATF in the gas tank certainly won't hurt anything, especially on an '85 Dodge. And who knows? It might even help.

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