If your utilizing Ultra from the 4 mix technology days , its terrible within chainsaws at any mix ratio , even in higher compression ported saws . The newer Ultra HP I have heard mixed stories of its quality & performance within saws . It seems that 50:1 ratio is what most users find the most optimal within its use apparently . Personally I believe there are numerous other quality oils today that far exceed any Ultra product at any mix ratio at a better price point . This coming from a 2 stroke engine enthusiast that has never used manufacturers oils in his sleds , bikes or saws . The majority of manufacturer oils are just adequate at a premium price point , unfortunately some are less than adequate within ported saw applications !