Actually Scott has a good point.
I had a friend who had his oil changed at a shop and they either forgot to install a new filter, or didn't tighten it down enough, and when his engine siezed he somehow proved that it was due to the shops negligence and they ended up buying his new engine.
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless