the polaris gold synthetic work very WELL on non-valved engines,
i've ran it 2 years with almost 6000 miles on my old 98 xc 600,
piston was not even wear out and no carbon deposit.

 

I'm using Amsoil Interceptor 2 stroke in my wife's Trailblazer, burns really clean and gives superior engine protection!

 

I've used nothing but Polaris since 1997 when I bought 15 gallons for $5 / gallon.
Have about 1 1/2 gallons left, then will probobly switch to Amsoil.
Two guys I know that race use Phillips Injex with their HPD'd bikes.