Not extra thick, just all thick Thick-thick-thick-nut. Im running DEX/MERC high mileage at the moment. Wanted something with the least amount of slip and the best heat management. Ok thus far. Not many miles yet. But I run it hard. Regeared to 11x31 double springs and a 210lb rider. Anyone know of a better fluid then what im running? Does anyone know what type of spring that is in the clutch?