My money is on BMW Momentum as the shop that screwed this up. I found that I had a stripped drain plug on my e46 when I did the first oil change after buying it used. The plug didn't leak or anything and it came out normally when I removed it to drain the oil, but when I tried to put it back in it just kept spinning. I had an indy shop install a Timesert a few months back and so far so good.

The bad thing for you is that you are going to have a hell of a time proving Momentum definitively messed up your car. I suspect they are all going to balk at taking any real responsibility.

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Profeshenal spellar