My book says it takes about an hour for the oil to drain down out of the injection pump, and it will retain about a quart. When you refill, preload your filter, and dump another 10 quarts in the engine, 11 quarts total. However, most of the time, I just use the whole 3 gallons, with no problems. I usually drive mine in the garage hot, pull the plug, let it drain over night, & refill in the morning. (Put a "don't start" note on the steering wheel, just in case!)