I own a 2005 corolla CE manual and a year ago (approximately 10000 miles ago) while driving it on the highway the oil light came up, when I noticed it I drove to the next parking lot and pulled over; the engine temperature didn't seem affected (at least 10 miles of driving and going 65 mph without oil). Though I will say he engine sounded strained or 'grungy'. When I checked the dipstick it was empty (odd because I had the oil changed not a 1000 miles before this), I filled it up with oil and while sitting there noticed that all the oil had simply leaked onto the ground. I had it towed to the nearest shop and they said the oil drainage plug had fallen out. They also said it looked as if the engine was fine. I took it to the shop where I had the oil changed and they too said it was fine.
The car has been driving since then without any problems (10000 miles like I said) or loss in gas mileage, though it sounds 'grungier' of late. Is there anything thing I can do to check it (oil analysis) or am I going to just have to drive it until it dies, or did I get lucky?