SAE 10w30 full synthetic.
The 750 STS Kawasaki Jetski uses 2 cycle engine oil. 2 cycle engine oil is specifically made for use in jetskis.
The recommended type of oil to use for a Kawasaki 610 Mule is API SF. Th610 Mule will hold approximately 1.5 quarts of oil.
10w30
I use Mobil 1 10W30 on my Ferris with a 25 HP. Kawasaki
10w40 Motorcycle oil
most use the engine oil for engine and trans
According to the Kawasaki site you should use SE class SAE 10W40, 10W50, 20W40 or 20W50 oil for the engine. You use SAE 10W oil for the front fork.
Use Kawasaki 10W30 motor oil or some good dino oil in it until you get at least 110 hours on it then you can change to synthetic. We prefer the use of 10W30 Mobil 1 synthetic or Royal Purple but ONLY after 110 hours otherwise the engine will nevr break in and the engine will burn oil.
I think it is a 2.5 horsepower engine. There are 4 oil formulas for Kawasaki lawnmower engines. I recommend you use the correct blend as stated in your owner's manual.
It is a 2 cycle so use a Synthetic 2 cycle oil any major brand.
automotive engine oil recommended by the manufacturer
I would use 10w30 Synthetic in your air cooled engine.