1940 gear oils

[std1940]

I am planning on changing my transmision and rear end fluids in my stock 1940 Ford Standard Coupe.
What is everybody using to make the 82 year old components happy?
Brands and weights?
Thanks Tom.

 

[Ken/Alabama]

I use 85-90 wt and you really need GL4 if you can find it. It’s not hard on the brass parts in the transmission.

 

[Bill OH]

I use 90w and a max of GL4 - stay away from GL5 in the transmission, ruins brass synchros.

 

[19Fordy]

I use this in my 1940 Ford transmission and rear end.
https://www.oreillyauto.com/detail/...gear-oil/mp03/80040?q=gl+140+gear+lube&pos=11

For winter driving you may want to use a lighter weight GL4.
https://www.oreillyauto.com/detail/...1-gallon/mp03/80039?q=gl+140+gear+lube&pos=13

I have found Oreilly sells this product at the lowest price.

 

[Ford Freak]

For years now I have used Sta-Lube GL4 / 140wt. in trans & rearend. I get it@ NAPA.- F F

 

[Tim Ayers]

85W-90 Sta-Lube GL-4 can be ordered in from any Napa dealer.

 

[FL&WVMIKE]

Gear oils labeled both GL4/GL5 should also be safe.

 

[std1940]

Thank You everyone for your wealth of advice!

 

[rotorwrench]

GL-5 is high EP and the extra pressure additive can be harmful to the soft metal bushings and thrust washers in a transmission. It works fine in the rear axle though unless you have a model T.

 

[FL&WVMIKE]

One more thing to add... For those wanting a high performance GL4 oil, Brad Penn/Penngrade sells a nice formulation... for a reasonable price. Below are links to places that it.
One specializes in Ford Toploader transmissions, but it can be purchased at other places as well. Summit is the cheapest at $8/qt. Can read reviews at Summit.

http://4speedtoploaders.com/store/gearoil.html

https://www.summitracing.com/search...ortOrder=Ascending&keyword=brad penn gear oil

 

[Ken/Alabama]

GL-5 is high EP and the extra pressure additive can be harmful to the soft metal bushings and thrust washers in a transmission. It works fine in the rear axle though unless you have a model T.

Or a Columbia.

 

[TerryOH]

Columbia has brass washers at the spider gears and both thrust faces of the axles. IMO stay away from the GL-5 in the Columbia.