Use the same stuff you use for your 2 strokes with one addition - get a tachometer. It is extremely difficult (very close to impossible ) to set the idle and top end PROPERLY without a tach. I also suggest and highly recommend, using OS "F" type plugs in ANY 4 stroke.

The primary difference in the fuel is the oil content - MOST 4 stroke instructions say to use 18% oil. I use the same fuel (Byrons 10% ) for both my 2 strokes and 4 strokes with no problems. My Saito 72 has over 4 gallons through it without a problem.

The other major discussion with 4 strokes you will encounter is whether or not to use castor oil in the fuel. I add a couple of ounces to a gallon of fuel. While I do get varnish build up, I like the security of the castor if I get a lean run.