The Stovebolt Site Forums The Shop Area Driveline Correct Lubricant for Transmission & Rear Axle

I have a 1946 3600 ¾ ton truck that I am in the process of getting running. I am getting confused on the lubricant for the transmission and rear axle and having a hard time finding SAE 90 lubricant. I found an SAE 90W Mineral Gear oil API GL-1 at NAPA which seems to be okay for the transmission. The manual says not to use mineral oil lubricants in Hypoid rear axles. If I am reading the vehicle information kit correctly it looks like the 3600 has spiral hypoid final gears. So it sounds like I shouldn't use this in the rear axle?

You are correct. Use the GL-1 mineral oil in the trans. Use a GL-5 gear oil in the rear axle. An 85/140 would work good in it.

George

My '40 model 1/2 ton pickup has the 4 speed box fitted by the previous owner. I'm replacing the oil and wish to know the quantity of oil required to refill it. I have a hand book which tells me that it is 51/2 pints, but doesn't state whether it is imperial pints or not. I'm in Australia and would like to know the quantity in litres please. can anyone help please?

The shop manual (US version) shows 5-1/2 pints for the 4-speed so it would be US pints. 5-1/2 pints is 2.6 liters (or litres for you Aussies )

There should also be a sight plug on the side or rear of the transmission for use as an indication of lube level.

Yep, Filling the tranny till oil starts coming out the fill plug hole on the side is the way to do that. You can't "sight" in there very easily, but if you stick your pinkie finger in the hole and can touch the lube, then there's enough in it. If your pinkie finger is too big to fit in the hole, get your wife or girlfriend to do it for you.

Thanks gents. When I started my career, measurements were links, feet, yards & miles. When we converted to the metric system, litres, which we learned at school, soon reverted to liters. As I'm old school, I still use the real spelling. As for poking my pinky into the filler hole, my claws are fairly large, as are the fingers, so I will use a piece of wire, dowel or similar.
Thanks again for all the help over the years.

I'm a little old school too, but not quite old enough to measure stuff in leagues, cubits, or hogsheads.
When the US government mandated metric (or more properly S.I.) units in design projects, I got a little familiar with it. That didn't last that long though, and I have pretty much lost that knowledge now and stick mostly to good ol' English units. But I have a neat little converter program when needed.