Hi Pud yes l will keep using castrol active 2t ,l put new needles and jets in the carbys an hr before the grab they are standed rotax specs for sea level and the same as the ones l took out l re syn the carbys also fuel lines are free and clear no restrictions mine is inverted also farri on my maxair .
When l pull the motor apart the crank and pistons have a nice coating of oil over them so dont know why for sure it grabbed..