Special fuel for Four Stroke Engines??

[Clancy Arnold]

As I said in an earlier thread, I am new to Four Stroke engines. I keep seeing advertisements for Four Stroke Fuel.  Do I need to buy special fuel or will my OS 91 Surpass II FS run reliably on regular 10 % fuel?

It is going to be pulling my new CL Scale model.

[Jim Oliver]

Clancy,
I used OS 91 Surpass engines for flying Senior Pattern for some years.  I used Morgan 30% Heli fuel (all synthetic lube) with complete satisfaction.  The higher nitro gives 300 or so more rpm but the biggest benefit was much better idle and throttle transition.

No experience with 10% nitro in this engine, but 20% should be OK if idle and transition are important to your application.

Cheers,
Jim

[Bob Reeves]

The important item is to use all synthetic fuel and use an after run oil, Castor will gum up the valves. Not sure what Saito recommends but I wouldn't use anything with less than 20% oil. Powermaster YS-20-20 is perfect and heard through the grapevine they are selling to individuals again.

[SteveMoon]

Clancy: Bob's right. You want a fuel with 20% nitro and 20% all
synthetic oil. Castor oil will form deposits on the valves and hamper
performance of the engine.

Steve