Not a real tractor, but a "super, zero-turn-radius 44" lawn mower" .Its been very difficult to find the correct oil for the "automatic-transmission" . . . Synthetic motorcycle 20-50 seems to be close , but this is both expensive and hard to find.. Also, the fluid is filthy..the time has come for a change ...I'll use the brake fluid gravity method - hope it works .. But, what oil is best !?? I will appreciate any input..