Warner T18 Oil type.

[DMiller]

Hey there,
I am probably opening a can of worms here. but, here it goes. 1971 F250 4 speed Warner T 18 transmission- what oil should be used? I have 80/90 wt.GL5 rated oil in it now, it is my understanding that this GL5 oil may cause corrosion in the gear box. 50 wt. is factory recommended, but I had no luck finding 50wt. gear oil. Valvoline makes a 50 wt. VR1 racing oil, is this what I should be using? Please clear this up for me if possible, thanks.

[Canuck]

Nothing wrong with what you have in there now but in a cold climate, shifting is stiff until it warms up. I've hear that some put 50wt motor oil in their T-18 but I wouldn't do that. Motor oil contains detergents that suspends particulate in the oil (so it can be carried to the oil filter for removal). In a gearbox, you obviously don't want that.

[Calfdemon]

I did quite a bit of reading on this topic recently when I was working on a T-18 for my friend's truck. 80/90 seems to be the most popular oil to use and this was coming from a lot of Jeep sights where that trans is very popular among rock climbers. There have been people running 80/90 in them for many years without any problems, so I think it is safe to go with that. As the previous poster said, other than the 80/90, some people put in 50 for colder climates so they can shift faster. But in warmer climates, 80/90 is all the T-18 needs.

[DMiller]

Thanks Guys,
I will stick with 80/90 wt. thanks for the info.