After doing even more research on this and some discussions with some knowledgeable people on this topic I'm going to use my 2 stroke fuel also in my four strokers. 15% nitro and 20% oil. You may lose 100-300 rpm because of the replacement of oil instead of the alcohol component but the other side of the coin is the engine will last much longer and if your a sport flyer that is an easy trade off since that small an rpm drop is negligible (most of use overpower anyway).

I think unless you are a maximum performance competitor and don't care about burning up engines much sooner than necessary just in order to tweak a couple hundred extra rpm than going with the 2 stroke fuel w/20% oil is the answer. Even Saito as stated above will void the warranty if you use 4 stroke fuel! That should tell you something...

I guess it's a matter of application...all out performance vs. engine wear and longevity. For the 90% that are sport flyers I would think that longevity would be preferred.

Now I just have to burn the rest of my 4 stroke gallon off! Maybe I'll add an ounce of Klotz since the motor is still semi-new.

Also, Gene mentioned to use an after run oil but also should add to that to avoid certain after run forumulations in certain engines as it could damage o-rings/seals.