Today: Tom and Ray investigate a very pricey "who-dunnit."

Dear Car Talk

Dear Car Talk | Jun 01, 2009

Dear Tom and Ray:

I have a 2003 Infiniti FX45 that was due for an oil change. I had some time to kill, so I went to a Wal-Mart Tire and Lube Express. I left the car, and when I came back they said they couldn't do any work because there were guard plates in the way. I thought that was odd, since nobody else has mentioned that being a problem. But I figured no big deal, I'd get it done at my usual spot. When I took it in there, they said they couldn't work on it because the oil pan was covered with silicone. Apparently, Wal-Mart must have lost the oil plug, used one of their own to plug it and siliconed it all up so it wouldn't leak. Estimates to get this fixed range from $1,200 to $1,600 for parts and labor. My question to you is this: How do I approach this? I know this is more of a legal issue than a car issue, but it seems like you would have seen these types of situations before.

-- Eric

TOM: Seen them? We've caused them!

RAY: This is a mess, Eric. And unfortunately, at this point it's going to be very hard for you to prove who made the mess.

TOM: Typically, what happens is that mechanics overtighten drain plugs. When they get overtightened enough times, the "receiving" threads in the oil pan get stripped and the plug leaks. If it's not leaking too badly, a bead of silicone can keep you going for a while longer.

RAY: But eventually, you'll either have to use an "insert" to "replace" the oil pan's threads, or, if that doesn't work, replace the oil pan itself (it's $1,200-$1,600 on your car because the engine has to be removed).

TOM: A lot of oil-change places will even refuse to work on a car that has silicone around the oil plug because they know it's going to fail soon, and they don't want to be blamed.

RAY: Wal-Mart's explanation doesn't make sense to me. I'm not aware of any "guard plates" that block the oil plug on the FX45. Is it possible that they lied to you? It's possible. Perhaps some guy there has made a bunch of mistakes and tried to cover up this one so he doesn't get fired.

TOM: Or perhaps you misunderstood them. Maybe it wasn't the guard plates that made them refuse to work on your car. Perhaps it was that there was ALREADY silicone around your oil drain plug.

RAY: There's one way to find out if they're lying. If you or your other mechanic checked your oil immediately after leaving, and it was brand-new oil, then they DID change the oil, and they're responsible for the condition of the oil pan.

TOM: Right. Obviously, if they removed the plug, the oil would have drained out, and they would have had to replace it. Only then would they have had trouble reinstalling the plug and needed to apply silicone.

RAY: But if the oil is still black and dirty, that means they didn't touch your oil plug, and the silicone came from some previous oil change.

TOM: These are difficult cases, because oil plugs often strip gradually, over many oil changes. And since you're obviously promiscuous about your oil-change locations, Eric (I know, you had time to kill, Wal-Mart looked fetching, one thing led to another), it's very hard to prove that one particular shop was entirely responsible.

RAY: But if your oil is brand-new, then you have a pretty clear case that Wal-Mart is the responsible party, since they specifically told you they didn't change your oil.

TOM: In that case, what you need to do is sit down calmly with the shop manager there, lay out your case and ask him to cover your new oil pan. All shops have "bonehead" insurance for just this type of accident. They may need to invoke their policy.

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