So I am looking to change the tranny fluids in my trucks. The '64 F-250 has a 4 speed I think it's a T-98. The '66 F-100 has a ford light duty 3 speed. I'm a little ignorant on the new types of gear oils out there, GL-4 GL-5 ..... What works best in these old trucks?
Thanks. john

 

You're supposed to run 50W engine oil. I just run any old 80W-90 in mine though.

 

From what I could gleam in the manuals it was 50wt in the four speed and 80wt in the three speed. But then there is all the different ratings and clasifications: limited slip, gl-4, gl-5. I've read in some threads where some of the rated weights are not the same as when the equipment was designed, or are not for use with certain kinds of gears (helical vs.std) Wanted to see what others were using.

 

Don't use GL-5, it has additives that will eat up your brass synchros. StaLube still has GL-4, I get it on Amazon but some auto stores still have it, I think Napa had it last time I checked. 80-90 will work fine in both.

 

I use GL 4 80-90 for both trans and rear axle. Recently change and found a gallon filled both with approx. a cap full to spare.

 

Thanks. That was the info I was looking for. Found some Stalube GL-4 at a Merels auto supply. When I mentioned why I didn't want the GL-5 the guy behind the counter said that there were some mazdas that were having similar problems with it.

 

I got a 98 f250 5.4 c.o.p, with pat sys. and a 94 Lincoln 4.6l coil pack non pat system I'm over hauling my 5.4 is it possible to put the 4.6 into my truck? so Iv heard u could use the 4.6 block with the heads of the 5.4. Heard their is only a 2 inch diff in the decks.rest was same heads. Values if the same.