as long as you do not heat the oil to the point of damaging it (burning/breaking down) then it is my understanding that the oil never wears out. I have heard that the additives will wear out but the base oil itself will not. I would personally feel uncomfortable with doing that in my car as changing the oil will remove any contaminants in the oil. the debree should get trapped by the filter. a friend of mine in high school was given a dodge dart as a first car from his father. his father was the original owner and never changed the oil or filter. eventually when the engine went down a quart, he would add a quart. he would say, after adding a few quarts you have esentally changed the oil. when his father gave him the car he told him to not change the oil but to continue with the set course. the car never smoked and only needed oil added every few months. all this and the car had over 100k on it. well shortly after getting the car, Robert (my friend) changed the oil. immediatly the car started to smoke and burn oil. no amount of STP or other additived would do a thing to change it. needless to say his father gave him a big rash of shit over that. they ended up putting a running used engine in the car. bob
