How good of a flush would I need to swap over to synthetic? I mean will it mesh with residual power steering fluid? I remember back in the day a friend mixed synthetic 2 stroke oil with standard 2 stroke oil and it turned to jelly, cost him about a $4k power head on a bass boat.snoball said:Elixer, Royal Purple, or good synthetic will work great and is what PSC recommends. The Elixer has seemed to work best for me.