We had an oil change done at a quick lube type shop. After 36 days and 2500 miles driven, the oil drain plug fell out, resulting in severe engine damage. There was no oil leakage or any sign of trouble up to the point where the plug came out; no oil in the driveway, or parking spot at place of employment.
We have gone through the process of filing a complaint with the oil change shop, and both their owner and insurance company have denied liability, even though they were the last to have touched the oil drain plug.
What could cause the oil plug to just come out, if not for that company's possible negligence or shoddy workmanship? Have we just driven the car too many miles to assign blame to any party?