Why to change your oil

I work at a ford garage and the other day a guy came in and wanted his oil pump and oil pan replaced on his 97 f150. Thats fine until we brought it in, it sounded like the bottom end of the engine was gonna blow out of her. So the customer was pressuring us to cover the truck for a new engine, after all the truck only had 138,000kilometers, and he claimed the oil was changed regularly. So after some crafty bargaining on the customers behalf we were ready to help him out, that is until we had contacted the local UAP/NAPA who had serviced his vehicle last. Now heres where it gets funny, The mechanic at UAP told us that the last time the truck was in for an oil change, he had to heat the bottom of the oil pan with a torch in order to get the oil out. Moral of the story, had he maintained his vehicle we'd be helping him put the engine in his truck, not laughing at his stupidity. :disappoin