I was asked to reply to this thread and specifically about Motul 800 2t, Maxima K2, and Bel-Ray H1R, so here are my two cents. These are great oils in the lubricating and varnish removal departments, the problem falls to the ester base that is used for our chain saw applications. The ester is a group V oil witch is normally used only for additives. The reasons that ester is not a common base stock are the tendency of ester to (attack rubber seals and cause swelling and deterioration), not a huge problem in motorcycle applications. But when you get into using it in a chain saw that has a rubber diaphragm, for a fuel pump, rubber flapper valves for carburetion control, and on a lot of models a rubber intake tube it becomes a problem. Another disadvantage is that ester reacts with water and can hydrolyze with heat. Not a problem for some saws as the gas tank is separate from the engine but I would not run out and use any ester product with say an old Echo that has the gas tank made into the casting. Now if you do not mind the extra maintenance this may cause (I have not tried them my self) then try them out, as ester is a great lubricant because of its tendency to cling to positive charged metal. Now in a PAO based oil group IV, ester additives can be a great thing because certain PAO’s shrink seals so the ester can counter act that shrinkage, but the two have to be balanced. Hope this helps someones choise in oil.