Differental oil?

[Kerrigan]

What lube oil is recommended for the differentials in the 1980 D-50, without a non-slip setup, just straight gears? Does it need a GL4 oil like the tranny?
Rather stick with a dino oil than a synthetic ...

[camoit]

85W-140 or 80W-90 It's just plain old stinky gear oil. I use 85W-140 because I buy it in 5 gallon pails for the concrete trucks.

[PowerRam348]

you can also use 50/50 gear oil and lucas oil stablizer. i use 100% lucas in my differentials front and rear, and i put 25% lucas and 75% gear oil in the transfer case and tranny. stuff makes the limited slip perform better, its like liquid locker for your diffs.

[pennyman1]

I run 80/90 royal purple gl-5 lube with no issues

[PowerRam348]

that's spendy stuff that royal purple.

[pennyman1]

Ya it is, but its a one time change - don't think I'd buy it again though, not worth the money.