Yikes! That just happened to my Dad's car last Saturday. He doesn't drive but his caretaker was taking him to breakfast in his Buick. They started down the hill from his house and the oil filter fell off and the oil started leaking out. Luckily they made it back up to his house and turned the car off before all the oil leaked out and the engine seized up. Dad's neighbor found the filter in the road and went to buy him a new one when he discovered the one that fell off wasn't even the right filter. We had the oil changed months ago so everyone is amazed that filter stayed on so long. Fortunately everything is okay with is car and it's running fine now.