1939 Ford Transmission Gear oil
 

I understand that a Hypoid, 90W, NON-SYNTHETIC Gear oil is best for this vehicle's transmission. Even 75W/90 is fine. Finding it is proving difficult for this rookie. The objection to Synthetic GL5 is that it eats up the brass over time.



One suggestion is to buy Tractor Supply straight mineral oil and add 25% Lucas oil extender available at Walmart. Anybody else use this concoction?


O'Reilly's Auto Store recommended Pure Guard GL-4 140. They also recommended ordering A Valvoline Quart bottle that specifically said "real" oil, not synthetic.



I did not think that it would be this difficult to "buy" the correct transmission gear oil for this 1939 Ford.



Reading the instructions in my Ford Passenger and Commercial Reference Book 1939 it specifically says to Drain, Flush and Refill with Gear Oil:
Winter S.A.E. Viscosity 90
Summer S.A. E. Viscosity 140


Also by "Flush" I assume it means to overfill with oil and let that flush out the old gunk.

Re: 1939 Ford Transmission Gear oil
 

I just use Sta-Lube GL4 gear oil in my '36. It's readily available on Amazon. I prefer the 85W90 oil as it shifts smoother and easier, however, I run the heavier 140W as it leaks less. I'm kicking myself for not installing O-rings on my car's transmission shafts.

Anyway, both of these lubes are rated GL-4, so they should be yellow-metal friendly... as far as I understand.

85W90 -- https://www.amazon.com/CRC-Sta-Lube-...3879714&sr=8-3

140W -- https://www.amazon.com/Sta-Lube-SL24...3879714&sr=8-4

Re: 1939 Ford Transmission Gear oil
 

O Reilys has GL 4 in stock on the shelf for $20 gal.

https://www.oreillyauto.com/detail/c...gear+oil&pos=9

Re: 1939 Ford Transmission Gear oil
 

Thanks!

Re: 1939 Ford Transmission Gear oil
 

Thanks!

Re: 1939 Ford Transmission Gear oil
 

I found this on the Internet............... Sounds like my go to mechanic in the Piedmont of SC was correct!...........
Warning About Gear Oil



GEARPLUS® SAE 80W-90 GL-4 Important .pdf file click to download

Sadly, Pennzoil no longer makes GEARPLUS® SAE 80W-90 GL-4

Never the less, the following still holds true:

WARNING:
All modern gear oil available today in local retail outlets is GL-5 grade. GL-5 grade gear oil contains sulphur compounds that attack brass and bronze. BMW transmissions and final drives made before 1992 contain bushings and thrust washers made of these metals. Any brand of gear oil that is GL-5 rated will attack bushings and thrust washers. Bench Mark Works LLC, I use only GL-4 gear oil and we have it available for sale to our customers at the online parts store.

Look for:
acc070A--$8.95--80W 90 GL-4 gear CRC brand

CRC® Sta-Lube® Multi-Purpose HYPOID SAE 85W90 Gear Oil API/GL-4:

CRC® Sta-Lube® Multi-Purpose HYPOID SAE 85W90 Gear Oil API/GL-4 is specially formulated to meet the unique requirements of API GL-4 service in manual transmissions and transaxles of passenger cars, light trucks and SUV’s. CRC® Sta-Lube® Multi-Purpose HYPOID SAE 85W90 Gear Oil API/GL-4 is blended from select base stocks and additives that yield a lubricant of exacting quality. This product is compounded utilizing specialized extreme pressure chemistry that provides protection of gears and bearings without being corrosive to bronze components. It contains foam suppressants to prevent wear, which can be caused by lubricant foaming and aeration. Effective rust and corrosion inhibitors protect metal surfaces from the effects of water contamination from condensation and the operating environment. CRC® Sta-Lube® Multi-Purpose HYPOID SAE 85W90 Gear Oil API/GL-4 resists the formation of varnish deposits on synchronizer components, thus assuring long, trouble-free operation.

CRC® Sta-Lube® Multi-Purpose HYPOID SAE 85W90 Gear Oil API/GL-4 gives the full protection of an SAE 90 under hard driving conditions while providing the flow characteristics of SAE 80W that are necessary during cold weather start-ups. This offers maximum lubrication and gear protection over a wide temperature range.

CRC® Sta-Lube® Multi-Purpose HYPOID SAE 85W90 Gear Oil API/GL-4 is designed for manual transmissions and transaxles of both American and import vehicles. It is formulated to be compatible with “yellow metals”, such as bronze, found in synchronizers and other transmission componenets.

BENEFITS:

• Meets the performance requirements of API GL-4 Service
• Will not cause glazing of synchronizer components
• Excellent thermal stability
• Outstanding extreme pressure and antiwear protection
• Prevents rust and corrosion
• Inhibits foaming and aeration


Bench Mark Works LLC
Craig Vechorik email [email protected]
3400 Earles Fork Road
Sturgis, MS 39769 USA
Telephone/FAX: (662) 465-6444
Toll-free order line: 1-800-323-7102
Hours of Operation
Technical advice: (662) 465-6444
All rights reserved.

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Re: 1939 Ford Transmission Gear oil
 

You can by gear oil for Ford transmissions and rear ends at Tractor Supply. It is gr1. It is stated on the bottle. My trans shifted a lot better with it.
It is really cheap. I think $13 for 2 gal.
I am going to put it in the 57 Chevy because it’s trans has brass synchro rings.

Re: 1939 Ford Transmission Gear oil
 

Andy: Is GL 1 equivalent to the gear oil that Ford used in 1932-48Ford transmissions?

Re: 1939 Ford Transmission Gear oil
 

Thanks!

Re: 1939 Ford Transmission Gear oil
 

Tractor Supply oil

Re: 1939 Ford Transmission Gear oil
 

Admiral What "o-rings" are you referring too?

Re: 1939 Ford Transmission Gear oil
 

So folks cut lands for oil rings on the two shafts that run through the trans case to stop leaks.

Mac VP advised to put a small smear of RTV in the bores in the case so when the shafts slide in, they are coated with some sealant.