I let what was in the oil pan drain out good, I got all of it I'm sure. I put on a Mobil filter, which is a small one, but it is the one that matches an AC PF47. I had two jugs to refill the motor with, a QS 5w30, and a Mobil 1 5w30. I measured out 3 qts QS and 1.5 on the Mobil 1 jug. I had some of both, and I was doing a little blending (why, I don't know, just wanted to I guess). Thought it was something to try. I am pretty sure I measured it correctly by the marks on the jugs, although, the marks on the jugs may not be perfect either.