Description : What does putting oil in a car, without draining the old oil do?
Last Answer : From Tom & Ray: When you overfill the crankcase by a quart or more, then you risk foaming the oil. If the oil level gets high enough, the spinning crankshaft can whip the oil up into a froth, like ... 's not much left in the glass-what you get is mostly air. And air can't lubricate your engine.