I'll be doing the same thing in this spring's prep work. One thing for sure will be about 4 oz. of Seafoam in the crankcase about 100 miles before draining, and then draining it hot. I'll just tilt it toward the drain hole and let it drip overnight. Figure that'll do.It's not what it sounds like. I'm gonna switch to AMSoil but there will be residual oil in the cases, right? I want the best bang for my buck so should I try to get all the regular oil out before I add the AMSoil? Is it possible?