Is it possible for a partially tightened oil plug to work its way loose after a few thousand miles?

Dear Car Talk

Dear Car Talk | Aug 01, 2002

Dear Tom and Ray:

I'm a lawyer, but I hope you won't hold that against me -- at least not too much. A client of mine -- a nice, hardworking lady -- has a 2001 Suzuki Grand Vitara. In January, she took the vehicle to a local quick-oil-change shop. During the next three months, she drove the car approximately 2,600 miles under normal conditions. Then one evening, while she was on the highway, the oil light suddenly came on and the vehicle stopped. She had it towed to the dealer, who told her that the oil drain plug was missing, along with all of the engine oil. The engine seized and now must be replaced, for around $5,000. My client believes that the quick-oil-change place failed to properly tighten her drain plug. The shop, and its insurer, claim that if the plug had been incorrectly installed, it would have come loose in far fewer than 2,600 miles. It seems hard to believe that the plug could take that long to come loose, but I can't think of any other rational explanation. What do you guys think? -- Jim

RAY: Your client is almost certainly right, Jim. Depending on exactly how loose the drain plug is, it can easily take 2,600 miles for it to come all the way out.

TOM: So, you've actually seen this happen?

RAY: Seen it?? I've done it! What happens is that if you fail to tighten down the drain plug properly, the vibrations from the engine and the bumps in the road will just work the plug loose, little by little, until it finally falls out.

TOM: If it's left really loose, it can fall out a few miles from the garage. We hate when that happens, because it makes it so much harder to deny responsibility!

RAY: But to answer your question, Jim, it's entirely possible -- and we think likely -- for a partially tightened plug to take several thousand miles to fall out.

TOM: So the oil-change place owes this lady an engine. And of course the insurance company doesn't want to pay. But that's tough. It's going to have to pay. And you and Johnny Cochran are going to make sure it does. Now go out there and help this nice lady get her engine, Jim.

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