| |
Click on image for the lowdown. 
====
| | | Forums66 Topics128,080 Posts1,055,953 Members48,430 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: May 2008 Posts: 210 Shop Shark | | Shop Shark Joined: May 2008 Posts: 210 | So when they say SAE 90 Hypoid for the transmission and rear differential...can I use SAE 75W90 API GL-5 in both? I just read that some older vehicles cannot handle the EP additive due to the copper on the gears? Has anyone heard of this? | | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | It will work fine in both.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: Feb 2001 Posts: 1,096 'Bolter | | 'Bolter Joined: Feb 2001 Posts: 1,096 | There is no copper on the gears .
In the gearbox, there are bronze bushings in the reverse idler layshaft .
In the diff, there are bronze alloy thrust washers behind the axle gears.
If one oil is good for the diff , it will be ok , in that aspect , for the g/box.
There are some oils that eat the bronze alloy bushings , I had this in my 4spd once , fortunately I checked it just a month later and saw the oil was heavily metallised , sparkly golden!!.
No permanent damage was done . | | | | | Joined: Feb 2004 Posts: 29,780 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,780 | The extreme-pressure additives in rear end grease can have a detrimental effect in some transmissions, but I don't think anything smaller than a Fuller Roadranger will show much of an effect. The shearing effect of the spiral teeth on the ring and pinion gears in the rear end creates friction that the film strength of plain oil cannot handle. The Roadrangers I used to maintain needed to use "straight mineral oil" as we called it, without the hypoid additives. Hypoid lube had a tendency to fill the grooves in the brass synchronizer rings with carbon, for some reason. If I tore down a Roadranger, and the synchro rings were black, I knew it had been running EP 90, not mineral oil.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Aug 2004 Posts: 242 Shop Shark | | Shop Shark Joined: Aug 2004 Posts: 242 | In my 1940 1/1/2 ton and my '42 Diamond T I use WARREN GL-1 gear oil. The transmission in my Diamond T has bronze thrust washers. I also use it inmy differentials. If i used a GL4 or 5 the EP additives would "eat" the bronze.
John
1942 G5106 1.5-ton Chevy cargo dump Gallery pageOld Dominion Stovebolt Society T/Sgt. Gott (28 years of service with the USPP) 1940 Chevy G506 4112 cargo dump 1942 Diamond T G509 969A 4 ton wrecker 1942 Ward LaFrance G116 series 2 10 ton wrecker 1944 Ward LaFrance G116 series 5 10 ton wrecker 1931 Ford AA with a WEAVER crane 1944 Sterling HC 165 tractor 1944 Autocar U7144T w/ 10 ton trailer
| | | | | Joined: May 2008 Posts: 210 Shop Shark | | Shop Shark Joined: May 2008 Posts: 210 | Sounds like there are contradicting opinions. I meant bronze but typed copper for some reason.
So does a 3 speed 1946 transmission and rear diff have bronze in the gears? Will the GL-5 additive eat the gears? What is my alternative?
| | |
|
|
| |
