So say you have a vehicle that is running fine that you checked the oil on frequently and there are no signs of coolant in the crankcase. Then you bring it into a mechanic for a transmission rebuild. On the drive home after that repair, it starts overheating and you pull over to see what things look like under the hood and discover that the oil looks milky. Then it goes back to the mechanic and he takes no responsibility for the issue that appears to have become a problem with the vehicle in his possession. His advice is that the engine is dirty from stop leak and the thing to do is install a new engine. Is it reasonable for the customer to suspect that something shady may have happened?