140 wt G-4

qmdv

qmdv

Well-known member
I ordered some 140 wt for my trans and rear end. What came was G-4 140. My question is will G-4 be hard on yellow brass.

Tim
 
Keystone 34 3W- I always read that gl5 was compatible with brass. Are you saying that it isn't? Stan
 
Some GL5 suppliers claim to be yellow metal compatible, but in general they are not. I'm not sure I would trust the compatible claims, I would go with the GL4. It meets the requirements without the risk.
 
If the GL-5 claims compatibility with MT-1 (manual transmissions), it's a safe bet.

There are two things required for the fluid to "eat" copper-bearing metals: high temperatures (mid-200's) and active sulfate formulation. Even with incompatible fluid, I doubt many old Ford trannies get up into the mid-200's. The problems with eating copper were mostly in big trucks, like Cummins-powered Dodges pulling 5th wheels.
 
Stan, I have been rebuilding trans for over 30 years now, my shop and the competitor shops in my area do not offer any warranty on our rebuilds if the customer uses fluids other that GL4 in olders brass blocker-ring transmissions especially in muscle cars. I had a hard time sourcing GL4 in Canada so I get it imported from the US.
 
The acidic additives in GL-5 Hypoid lubricants actually eat into the wear faces of the gears in order to provide the extra pressure capability. The sulfuric acid will eat away at softer metals and can cause free wheeling clutches to slip in the Borg Warner electric overdrives. GL-4 superseded the GL-3 mild EP many years ago. GL-4 is considered to be yellow metal safe since it is a mild EP with less acidic additives. Some brand names claim that they can now provide high EP without the acidic qualities but they won't tell folks how they formulated their High EP so I tend to err on the side of caution.
 
From the horse's mouth:
 

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Another explanation with no additive information. I just don't see how an inactive sulfate with bite onto the face of a gear tooth. It would be safe as a GL-4 if it is rated as a GL-4. They just will not explain how an inactive sulphate works or even what its chemical composition is. I'll believe it when they show the stuff for what it really is and how it works.

Here is one explanation: http://www.machinerylubrication.com/Read/28548/sulfur-used-in-lubrication
 
Keystone 34 3W- Went thru my notebook and realized it was GL4 that is recommended. Had a Senior moment. GL4 is what I used in my ******. Thanks Stan.
 
I did pick up a gallon of GL-4 140 wt at the auto parts store. They had to order it in. That is what I will put in my trans. I also have on the shelf a gallon of GL-4 90 wt.

Now for the rear end and steering gear I was thinking of using the 90 wt. Any concerns there?

Tim
 
Some folks like to use the John Deere corn head grease for the steering gears due to problems with seal leakage. Originally, SAE 90 was the recommended lube but a bad seal will mark a spot. A new seal should hold it OK. Many of the steering gears have a phosphor bronze bushing inside so they can be affected by GL-5 lubricants. GL-4 or GL-1 rated lubricants would be OK.

Rear axles have no yellow metal in them and can use any gear lube you want to use as long as they meet the recommended SAE rating for viscosity.
 
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