Eaton Fuller 10 speed oil

Delvac 1 transmission oil.

shell has it too.

 

Any good quality 50w synthetic

 

That was used back not to long ago, then suddenly they figured 50w would work. I’m running 50w right now and am planning to replace with 75w90. Bearings are a little to noisy/rattle when rolling on idle speed. With a recent rebuilt also on 13 spd.

 

I seem to recall that 50w oil is actually thicker than 75w90. Different scales are used to grade engine oil and gear oils.

 

From what i was schooled the 50 is thicker but its parasitic properties are much less. The hypoid gear type 75w90’s cling to and climb the gears more than the 50 which makes the trans shift heavier and harder. It also stays thicker and warms up slower in cold temps. One reason why the car manufacturers changed from the old gear oils to Dexron auto fluid in the 5 speeds. Using it won’t hurt at all but it may change the feel of the shifts.

 

The current lube requirement for all manual and automated Eaton transmissions is PS386 spec 40wt “use to be 50wt” and is backward compatible with all models. A 50wt transmission oil will also work. Keep the gear oil in the diffs.