Welcome back.
You sure it's been 10 years? The DX6i came out in 2009 +/-. Even so, if unused the tx and flight batteries are probably questionable.
10% or 15% nitro with 18% to 20% oil (
http://saito-engines.info/fuel.html ) Some say YS & Saito need 20% nitro. I'm a proponent of run them with whatever you used when you broke them in.
There is never ending debate between castor, synthetic or blends. S&W, PowerMaster, Omega - all are good.