I have run YS 20/20 high and low viscosity on my YS 80 and OS 32. The engines work great on both, but I prefer the low viscosity. WIth the low viscosity, you need to lean the engine slightly, because the fuel travels through the engine easier (Per the Powermaster reps).
Both engines produce great power with the low viscosity fuel (better than the high viscosity.....especially noticeable on the OS 32).
I purchased the fuel direct from Powermaster at IRCHA for $13.00 a gallon. I wished I purchased more than 6 gallons, but will catch up to them at another fun fly somewhere.
You will find more smoke with the low viscosity. I mean, it really smokes more; but according to Powermaster, it is because the fuel is burning more complete with the low viscosity and the motors are being better lubricated.
My flight times also increased with the low viscosity; an increase of about 3 minutes on my Fury Extreme 80 and about 5 minutes on My Caliber 30.
I cannot find the Powermaster 20/20 low viscosity locally. The LHS shop said they would not order it for me even though they carry the 20/20 high viscosity. I am going to call Powermaster directly and have them ship me a case (and let them know what the LHS said) if I can't catch up to the Powermaster reps at a fun fly before I run out of fuel.
Best Regards, Dario