I have a Arctic Cat 300 4X4 which has a Suzuki oil cooled motor with a wet clutch and a shared oil sump. This summer I'm going to use the ATV to till soil for a wildlife food plot. The speed will be slow and the ATV will be under a load pulling a small disk or drag, so not much air will be going through the oil radiator or around the cooling fins of the motor. I know that a synthetic will be the wisest choice for an oil. The factory manual spec is generally 10W-40, for temps above 50 degrees 20W-50 can be used. All oils should be JASO rated or not have moly or friction modifiers for the wet clutch. Locally I have Rotella T 5W-40 and Mobil 1 Motorcycle 10W-40, as well as an Amsoil dealer who can order anything. Opinions?