New to forum. My son purchased this Troy Bilt tiller with his home for 40.00. I have it running but needed to replace the clutch and recoil starter.(clutch froze and damaged the recoil starter) It starts and runs fine. I found a copy of the manual on-line and it needs 140W gear oil for the transmission which I want to replace. Haven't been able to get it. All GL-5 which I think is wrong for the brass gears. Is there any other acceptable gear oil for this transmission. All help appreciated