Frank,

Engine type/construction isn't fully defined. Are we to guess that this is an old OS .35S with a Gardiner piston/liner? Or? What is the rest of the construction:

Piston material?

Ringed or lapped?

Liner material?

Rod bushed or not?

Plain or ball-bearing supported crank?

It all matters....

Dave

      What total % should I use.  Can the engine get by  with less oil?

      Tia,

      Frank

We are familiar with the OS .35S (Stunt), but we don't know if it's the OEM piston/cylinder that's been chromed, or the B.G. ABC conversion.

To me, the rod and lower end still require a good amount of oil, with at least half being castor. If there is a problem with varnish buildup, I'd add more Klotz. I'd start with 25% oil for a fresh engine and reduce it to 22% after it has enough time on it...15% castor & 10% Klotz to start, then 15%/7%. Scrubbing bubbles cleans the goop off. Take lots of paper towels along!  Steve

     Thanks Steve:

      That is the information that I was seeking.

      I was always curious to know what percentage of synthetic oil do I need to keep an engine “clean.”

      Frank

When in doubt, ALWAYS refer to Randy Smith's pinned articles at the top of this forum. If the answer you need isn't there, it will be a rare situation. I wouldn't claim that 7% Klotz would prevent varnishing from castor oil, but it will help. And I haven't ever had any problems with internal varnishing, and not even much from external crust buildup.

My usual fuel choice is Powermaster 10/22, mostly because the R/C bods won't buy 5/22, so nobody ever stocked it. More nitro, better idle (maybe) because the glowplug will stay hotter (maybe). Either that, or the LHS guys push the more expensive 10% and know that "better idle" is going to impress the typical R/C bod. Basically, see what works for you, keeping in mind that too much oil isn't going to hurt your engine in any permanent way.  Steve