Hey...
Just had my SM318 3-speed transmission rebuilt (synchros bad, possibly from using GL5). I would like to put in the correct gear oil.
The manual states, "Either SAE 90 Multi-Purpose gear lubricant or SAE Straight Mineral Oil may be used". I heard I should stay away from the synthetic and GL-5 gear oils. I also heard I should use GL-4 gear oil. I also read I could use the "Ford Tractor Transmission Fluid Mineral Gear Oil" which is SAE 90 API GL-1.
I was looking to go with the Ford Tractor Transmission Fluid Mineral Gear Oil, which states it is GL-1. I do not know what is currently in the rebuilt trans now and just don't trust it. Good thing the trans has a bottom drain plug for easy draining.
Should I stay away from the synthetics? Is GL-4 better than GL-1?
