Perhaps something else was improperly done, which brings me to a different, but related, topic:
People are often warned of places like jiffy lube and such for stripping the threads in the drain pan. How do you surmise they do this? Are drain pans really that delicate? With a regular socket wrench, it's not easy to exert an incredible amount of torque. Do you guys think that they purposely try to over-tighten the plug?
I thought about this before when my sister told me about how frequently customers needed new drain pans at her work (Toyota Service department). She said there were usually a couple EACH DAY! Given, this was a huge dealership/service department, but I couldn't figure out why it was so common. Wouldn't these quick lube places be aware of the potential to over-tighten and try to avoid it? I mean, do these kids have that much less experience than, say, the kids that do oil changes at the dealership?
Then I got to thinking: maybe they cause this damage when trying to REMOVE the drain plug. Maybe in a hurry or whatever, they forget lefty loosey for a minute and accidentally way over-tighten the plug while trying their HARDEST to remove it. This seems to be the only way to mess "some" cars up, but others are just fine. Because you would think that each kid must tighten 20 or so plugs each day and all that repetition would result in SOMEWHAT similar torque exerted on each plug. So when they occasionally forget to reverse the switch on the socket wrench or whatever, they end up screwing it up and they KNOW IT when it happens. Then they're like, "whoops" and don't say a word. I dunno, what do you guys think?