Topic: transmission oil, diff oil


24bolt    -- 03-22-2021 @ 1:38 PM
  Hi Guys, I am a brand new owner of a 1945 1/2 ton, and new to this forum. Ford used 600 weight clinging gear oil because the seals would not seal with thinner oils. My truck seems to be a survivor, almost all original--so probably original seals. It's indicating about 48k miles, but who knows! The transmission is a non-syncro 4 speed. I'm leaning towards using the 600 weight, but wondering if modern synthetic gear oil makes the re-learning of double-clutching and driving a crash box easier, or just make it leak more? There are guys online saying they use modern thinner gear oil, but no comment as to what effect it has. Thanks, and if this has already been discussed repeatedly, I couldn't find it.


alanwoodieman    -- 03-22-2021 @ 6:49 PM
  most people use 90/120 wt doping in both units-trans and rear axle, I stay away from anything higher than GL4 and I also down here in the hot south add about 1/2 quart of lucas oil extender


TomO    -- 03-25-2021 @ 7:57 AM
  The 1946 Service manual states that 140 weight mild EP gear oil is used in the transmission and differential in the summer. 90 weight gear oil is used i the winter.

600 gear oil was never recommended for the V-8 era cars, pickups or heavy duty trucks.

If you vehicle leaks the 140 gear oil, you should repair it to preserve the truck and the environment.

You can purchase reprints of the service manual from most of the vendors found by clicking the LINKS tab on the left of your screen. It contains a lot of valuable information for maintaining you pickup. Here is a link to it on Mac's site:

https://www.macsautoparts.com/service-manual-ford-lincoln-mercury-soft-bound-book-224-pages-passenger-pickup-47-66950-1.html

Tom


osbornagain@yahoo.com    -- 03-25-2021 @ 12:56 PM
  Man, what a great looking truck!


24bolt    -- 04-14-2021 @ 5:50 PM
  Thanks guys, I put 75/90 Mobil 1 in it, and because it was pretty dark, I'll change it for the thicker it calls for in the hot summer. If it leaks, I'll just replace the seals, which are probably much better now. Like my buddy's old Jag that had leather seals!


EFV-8 Club Forum : https://www.earlyfordv8.org/forum
Topic: https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=17&Topic=14698