I have my 3 speed overdrive and am preparing it for my truck. When I put it in - what lubricant should I put in it? I believe the book says to use 90 wt. A friend (who has an overdrive in his panel) said he uses Castro 30 wt.

What do you all use 90 wt or 30 wt?

TIA

Dennis
-there is nothing stronger than the heart of a volunteer-