Admittedly I did cross-thread the bolt after changing the oil, but I've never done that before, making me think the new bolt was of a softer metal than the pan.

Thanks all, I had no idea of all the options, I guess I was a bit rash in accepting this one shop's opinion about the problem. I appreciate the input.

-Iain

Problem was, there's only one spot on the pan that's low enough to sufficiently drain all the oil, and it wasn't possible to re-thread the original hole due to it's location, so I had to replace the entire pan.
The entire bill came to $250 for a used oil pan, and about $200 more for the installation, since you have to lift up the engine for the procedure.

Point is, watch out for the quality of new bolts, and never cross-thread when changing the oil! It's a pretty high price for a little mistake.

First, let me say that this is NOT intended as a flame or sermon, I'm posting for the benefit of everyone.

Crossthreading, which I've done on occaision, is ALWAYS the fault of the "jerk" on the end of of the bolt, not the material which has nothing to do with the mechanics of bolt operation. Even if the oil pan had pristine threads, crossthreading is possible with the factory original bolt.

Oil pans on BMW's can be heliarc welded to repair the threads since it is cast aluminum, that's how I would have attempted to do the repair. Yes, the pan must be removed to properly repair stripped threads, a procedure well within the ken of a home mechanic. A second, less desirable method is thread inserts, helicoils which may or may not be available for short thread runs like an oil pan, and third and next least desirable is a retapping and use of a larger oil pan plug which are available for just this occurance, some "Jiffylube" type shops even carry them for the times they finish stripping out threads on overtightened oil pan plugs.

Pat Hines