Hot Rods Driven GL-4 Gear Oil Ate My Bronze Bushings !!

Too bad. Carquests seemed to have disappeared around here. One in Bismarck closed.

 

I believe that Carquest was acquired by Advance Auto and the former Carquest inventory was folded into Advance Auto.

 

Orillys near me used to carry 85-90 wt, now only 140 as others have stated. I recently found Napa online 85 90, and gave the part # to my store, delivered the next day

 

Here's hopin you get "stuck in gear" for a while............

 

Cut the crossmember out and make one that is removable. Thats what I'd do.

 

This is exactly what Paul at Liberty's gears told me he uses in syncro shifted gearboxes recently

 

Gear oil viscosity numbers don’t directly cross to SAE numbers iirc, in terms of viscosity do they? They are different is my understanding.

If you look in the original operator’s manuals they might spec a gearbox with either a straight SAE 50 mineral oil or a 90 wt gear oil. They would at least be be similar in viscosity. And the SAE 50 mineral oil (if you can find it) definitely won’t have the type of EP additives or sulfur that might attack bronze synchros and such. Sometimes simple really is better.

 

Yes, transmission oil and engine oil is graded by different scales, where the transmission oil gets far higher numbers for the same viscosity. This was done to reduce the risk of people confusing the oils with each other and putting transmission oil in an engine or vise versa by accident.

 

GL-1 90w is still available. I have used it in pre-war motorcycles, not sure what car trans one would use it in.

 

• 76? Is that all? Forget your age. I'll be 83 in May; In warm weather months after lunch, I ride bicycle 14 miles a day in the country each weekday, and then go to the garage to work on whatever. Spend half an hour on the exer-cycle in the winter; just finished blowing snow at home and at my garage, going to have a sandwich, get on the exer-cycle, and then head to the garage to work on a '39 Dodge sedan I'm upgrading for my grandson.

 

Yes, you're both correct. To clarify, the SAE has 2 different sets of viscosity grades, SAE Engine oil viscosity grades, and SAE Gear Oil viscosity grades. Each viscosity grade consists of a range of viscosity, measured at 100C. And just to make things more confusing there are also ISO viscosity grades, and AGMA (American Gear Manufacturers ***oc) viscosity grades as well, and they're measured at 40C. And to top it off viscosity can be measured and reported as either Saybolt Universal Seconds (SUS), or Centistokes (cSt). Centistokes is the modern method in use, but you still run across SUS numbers and you have to be able to cross them over.


As you can see in the chart, an SAE 90 grade gear oil encomp***es a fairly wide range of viscosities, and can be the same as the middle of an SAE 40 grade Engine Oil, up to the top of SAE 60 grade EO.

Lubricant companies purchase a base oil from a supplier that meets the specifications, and that base oil can be anywhere in that range of viscosities and still be a 90 grade oil. The consumer doesn't know whether it's toward the high end, the middle, or the low end of the 90 grade specification. The bottle of 90 grade gear oil you buy may be as thin as a 40 grade engine oil, or as thick as a 60 grade, and you wouldn't know it. Pretty wild, eh?

As I posted earlier, most truck manual shift transmissions now use a straight 40 grade engine oil viscosity oil, which is a fairly new specification, previously they used 50 grade, and that goes back several decades. I guess they moved to lower viscosities to improve fuel economy. As Truck64 pointed out, they have no EP additives, anti-wear protection is provided by Zinc compounds, which are not as strong as EP additives, but work fine in transmission applications, EP performance is not needed.

There you go, clear as mud....

 

By the way, the technical definition of viscosity is "Resistance to flow". We use words like "thick" and "thin" to describe it, but really it's a measurement of a fluids resistance to flow. A low viscosity fluid has little resistance to flow, it flows easily; and the opposite for a high viscosity fluid, it has a lot of resistance to flow.

 

Amsoil sells GL4, I had to order directly from them. Within a few days I got my box with oil. 5 years and no issues so far.