I ran one of those boxes in my model T and a friend recommended STP oil treatment. I found that it worked good.
You want to look for 00 weight grease. It is a light weight grease. It will run, but it will take all day for it to run off a tablespoon. It is the corn head grease the others are talking about. It is used on auger type gear boxes such as snow blowers and roto-tillers as well. It should be formulated to not attack brass and bronze gears.
I believe 90 wt gear oil WAS standard in vehicles of that era but they always ended up leaking so chassis grease was used buy most garages to save customers $$$.
John Deere cornhead grease works great in my 1953 Willys CJ3B steering gear and the gearbox on my Woods 6ft. bush hog mower behind my tractor.
It works well and is easy to find. NLGI #00 is a "self leveling" grease - same thing as "corn head" or "pickerhead" grease. Auto parts stores carry NLGI #2 aka chassis grease which is not suitable for a gearbox. They probably won't have 00 grease in stock, but they will have STP.
This Penrite semi fluid steering box grease is the stuff you need to stem the leaks . #LUB009 page 24 http://www.restorationstuff.com/pdf/RestorationSupplyCompany.pdf
"John Deere cornhead grease" I really thought that it was a smart aleck, but funny reply. Now I know something new!
I use moly bearing grease which I usually have on hand with a little 90W gear oil to liquefy it. Just grease alone can get shoved to a corner and not lube over time. I reckon any lube will work as long as it is always in contact with the moving parts and doesn't leak out.
Every manual steering box I have ever touched, from the 1940's and older, has gotten the John Deere Cornhead Grease. Simply remove the cover and drain out the old stuff. Then pack it in.... One benefit is if your old box weeped a little, this stuff seems to not weep out. A Great product! Sent from my Moto Z (2) using The H.A.M.B. mobile app
50/50 oil and grease works as long as it flows back to level in a reasonable amount of time. 00 or 000 NGIL grease will flow. Straight gear oil if you have good seals.
Harbor Freight has 00 grease. I bought a bottle when I was in Texas and brought it home. For some reason I couldn't find any in Canada, even the John Deere dealers didn't have it. Tractor supply has it too. https://www.tractorsupply.com/tsc/product/super-s-cotton-picker-spindle-grease-00
I've been using CV joint grease which appears to possess similar properties to the cornhead stuff, namely it flows back after a component has passed through it ensuring the parts are permanently lubed, unlike regular grease which gets pushed out of the way and stays there. Only used CV grease as it's readily available to me. I wouldn't know where to start looking for cornhead - not much farming / farming supplies around here. Chris
Bet that bottle still smells like rubber. EVERYTHING from the Freight smells like rubber!! Love going there just for that smell. And for my shop full of their tools too, of course!
Not real rubber smell - HF smells like Chinese Rubber made with fish oil. Sent from my iPad using H.A.M.B.
You can get JD cornhead grease on Amazon. When I bought it, options were something like one tube for $20, two tubes for $30, or a case of 10 tubes for $50. I opted for the case. So now I'm either set for life, or the family can expect some weird Christmas gifts down the line.
My little brother used to bring girls home that smelled like Chinese rubber made with fish oil. Knew what 'it' smelled like...just never could put my finger on it!