- Nov 16, 2021
I have a older garden tractor (Wheel Horse) that has a gear drive transmission. The manual calls for a straight SAE 90 (GL-5). I have done a lot of searching and it is very difficult to find. If I went with the standard gear oils (85w-140 or 80w-90 or 75w-110), GL-5, which alternative would you use? What would be the downside to not staying with the SAE 90?