Oh and by the way, i know you have a separate post about amsoil, but I switched for my mowers last fall with the exact same oil, and It may be me but i have noticed a difference with the motor oil. It definately does come out cleaner at the reccomended intervals on my kawi 23 hp.
I also started using the amsoil saber 2 weeks ago. It woke my redmax blowers and weedwackers right up real nice, absolutely can tell a difference. but it took about two or three tank fulls in each to realize. they start up better and rev up faster too.
If you like those products try the amsoil quickshot. that made even more of a difference than the oils did. I have tried a bunch of fuel treatments without much difference in the performance, but WOW the quickshot absolutely made a difference. I used it in all my chainsaws and the difference was much more than i was expecting. my chainsaws usually took four or five pulls to start after sitting for a month or so, now it is like one or two pulls!