2007 at the Hammond Barn

[Barry Churcher]

I think Paul is right. The best fluid in my mind is 80/90 gear oil GL-1. You could also use GL-5 but it must say yellow metal safe. If it doesn’t it will have too much of the extreme pressure (EP) additives , sulphur and phosphorous, which over time attack any yellow metal in the units. I try to stay away from synthetic fluids unless specifically required for some of the newer vehicles. Changing the diff fluid on trucks without posi. up to about 2000 is NOT required under normal conditions. There is little heat to break down the oil. Outside contamination such as mud or water (usually 4X4s) makes changing the fluid necessary. Oil technology has advanced so much in the last 60 years that we can’t compare what was in the vehicle to what is available now.
Cheers,
Barry