<font size="4">I've been flying for over 50 yrs. Used everything from white gas and 90 weight oil to the modern fuels offered today.
I now use only (Saito) 4-stroke engines from .91 to 1.25 and run 30% nitro exclusively in all of them. I add NO xtra oil to the commercial fuel I buy. My engines run like they did when NIB. And they have lots of hours on them!
The commercial outfit that sells my engines (GP) says they run 30% fuel in all the engines they sell. Good 'nuff for them, good 'nuff for me.
When (and if) any of my engines start to give up the ghost (hard to start .. loss of power .. etc.) and do this before they should (at an early stage of their useful life), then I'll look for something else to use.
BUT since I've been doing this for sooooo long, I'll probably die before having to change.
Best thing about this hobby is  .. do what works best for YOU!
Now .. let's go flying.</font>