I run 10% with an oil content of 20%. I always run fuel with castor in it. Usually 4 or 5% castor 2 stroke fuel. I have Saito's from a 45 to 120's. i have no problems. I also believe that Saito reccomends some castor in thier instructions. It is personal preference, i like castor. The reccomendations on running rich is absolutely right. 4 strokers don't like lean runs. You can cause damage easily on a very lean run. Just be careful with your settings. I set mine and forget it. If it is very hot and dry or cold and wet I may have to adjust the high speed needle only a few clicks. I rarely adjust my needles once set. Go ahead and get you Os and enjoy it.

Mark Shuman