Drained my coolant the other day outta my 01 VMax 500. Stock coolant at 4k miles. When I drained it, it had a dirty green color and there'd be streaks of the black/dark green. Gonna fluch the system as soon as I get a chance. Might it be the head gasket? Yet it didn't seem to be puffing white smoke, and seemed to be running fine the same as it has been since 3700 when I got it for the most part. Going to check compression when I get the chance, any suggested #'s (110-120?) + or - a few psi from each cyl. I also dumb @$$ me, the overflow tank was empty and all I had around was yammy high perf(red). would mixing red with the green cause this? PLanning on AMSoil coolant any one have any problems with it?