RE: Fuel recommendation for YS63FZ-S
I have flown the YS 63 on Powermaster 20%, various helicopter blends 20-30% nitro, Magnum I & II, currently flying off a stock of Magnum I. Engine has liked all these fuels. Have never tried going below 20% nitro because of advice from many sources including the manufacturer and the US distributor. It likes 20%, likes 30% even better. Have never used the Magnum DZ blend, but I'm told it uses a lower viscosity oil than the other Magnum blends, and the DZ likes that.
I will add that I find I have to retune both needles whenever I change from one fuel mix to another, so it really helps to pick one fuel and fly that the whole season. Same fuel new jug runs the same, so once you get the tuning right you're good for the rest of the year. We get a group of five or six guys and place a pallet load bulk order with Magnum every year to get good pricing.
Magnum fuels also work great in most two-strokes, so you can run just about anything other than the big Moki & MVVS engines on Magnum or other high-nitro fuel. My Asian two-strokes run great on high nitro, lower throttle to cruise on, more grunt on up-lines, same tankful gives more flying minutes so it doesn't cost any more.