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What type of transmission oil for 1928 Studebaker GE Dictator - Straight Cut Gears


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to GE Dictator 1928; I use 90 wt mineral oil in my 27 Commander. Studeboy say's he is using 140 wt. and I might just try that since it's a little hard for me to go into 3rd without a little grind. This has been discussed here before, but would still like to hear from metal experts. And, it does take a different driving technique on our older cars.

Commander Dave

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Someone else just told me they use 250W. I was wondering about the mineral oil as it is thicker than I think the 600W stuff used in Model A's.

My problem is that the transmission shifts fairly good when it's first started, but after the car drives a while and is warned up, it grinds basically no matter what I do. I even had a situation where I had to take a hill in seconfd gear at aboyt 10-15 mph because when I would downshift, it took so long for the transmission to slow down enough that i could put the car in third, that i lost all the momentum I had built up in second, that I'd have to down shift again, so i just left it in second and put up with all the curses and finger jestures from the people behind me.

Is there any yellow metal in these transmissions that we have to worry about?

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Yes, there are bronze bushings in the transmission. Use 90 weight mineral oil with no additives.

No additives would be a bad idea. Protection against oxidation, thermal degradation, rust, copper corrosion and foaming is also important. You want all of these protections. The EP additives are reputed to corrode copper so you want no or mild EP additives.

But do EP additives really corrode bronze? I want to see documentary evidence about it. I would expect there are anti-corrosive additives in the oil too.

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I have done a little research on gear oils. I found this at http://www.widman.biz/uploads/Transaxle_oil.pdf. This paper gives some science and engineering data about it in a way many can follow and is not based on hearsay.

"The gear oils of a few decades ago had lead additives that were effective at wear reduction, but not

very good for the environment. A long time ago they began to be replaced by gear oils with a

phosphorous additive (in itself a decent anti-wear additive) with active sulfur to grip hold of the gears

and create a very solid sacrificial layer of material that could be worn off, thereby protecting the gear

surface. Eventually it was discovered that the active sulfur was causing corrosion of brass and other

soft metals used in differentials and transmissions.

"Somewhere around 20 years ago a deactivated or buffered sulfur was developed that would react with

the phosphorous to create the protective/sacrificial layer in the conditions created in the gear boxes

(temperature and pressure) without being corrosive to the brass, copper, etc. This additive system is

used in most gear oils today."

We are talking about a non-synchro transmission so a GL-4 oil should be fine for you. The additives won't attack the bronze bushes. The paper above gives some "recommendations" towards the end.

If you have a synchro transmission, you had best read all of Richard Widman's article given above. Don't use GL-5 oil. The EP additives won't corrode your synchro rings but are stronger than the bronze and will peel off a few molecules of bronze every time the synchro's disengage.

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I've been using Pennzoil's Synchromesh manual transmission fluid for years. It is designed for transmissions with bronze or brass parts. I did call their customer service line once to ask if they would recommend it for Studebaker transmissions. In this age of suing everybody for everything, the guy explained that they had not specifically tested Studebaker transmissions and therefore could not give an absolute endorsement. However, he said that, in general, it is a good fluid for any manual transmission with brass/bronze parts.

Also, remember that motor oils are rated for viscosity at 212 degrees F while gear oils are tested at 70 F. That means that a 90 weight gear oil is about the same as a 40 weight motor oil in terms of viscosity. The chemical additives are different, however. So, if you can't find GL1 fluid, you can always use 40 or 50 weight non-detergent motor oil in an old manual transmission.

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After reading all the responses about what lube to use in antique Studebaker transmissions, I think I know why my 33 Rockne transmission gears are always grinding. I took it out today for a ride before the snow flys here in Northern Ohio and the transmission didn't hardly gring at all. So with it being 39 degrees outside the viscosity of the lube was a lot heavier therefore resulting in easier shifting. I will change the lube before spring, just need to pick the right one. I really enjoy this web site and reading about the old Studebakers, I just finished my restoration in August of this year. Merry Christmas to all you Forum readers.

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My solution to your problem is to drive your car more and you will become more skilled at double de-clutching. :)

I double-de-clutch both ways - quicker change upwards too. Warmup is terrible as the viscosity of the oil changes. Oh, when going down change early, don't leave it 'til too late. And feed it a good bootful of revs as you have the trans is neutral and your foot off the clutch. Hope this helps.

My father, who grew up driving "crash" gearboxes, didn't pussy foot around with gear changes. Just ram it through. No grinding gears, just a quick, big graunch-clunk. I nearly had a heart attack when he first did in my 1930 Dodge.

Edited by Spinneyhill (see edit history)
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Most tractors specified 140wt transmission oil up until after ww2, with 90wt specified for winter use, They have the same kind of gears as these old cars do. Restoration supply company still carries 140 wt. If you want to go with 90 wt oil, the right type is sold at all Tractor Supply Company (TSC) stores. They label it as Ford transmission oil. The old Ford 9N's used the stuff for hydraulic as well as transmission oil. There are tons of those old Fords still being used so the oil is available.

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I used a 85-140 wt. gear lube in both my rearend differential and the free-wheeling transmission and the gears in the transmission still were grinding. I have the original Pennzoil Lubrication chart for my 1933 Studebaker Rockne and it says to use Pennzoil Lubricant 409 from a temperature of 0 to +40 degrees in Winter and 416 above 40 degrees. Does anyone know what the conversion would be from Pennzoil 409 in Winter and 416 in summer from 1933 to today's lubricants.

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Any ideas? I am having trouble shifting the car and i think a light weight tranny oil was put in.

I was just told to use 90W Mineral oil for the bronze worm drive rear end of a 1934 Nash Ambassador and it was the thickest stuff I've ever seen. Should I be using that??

Thank you!

Keith Gramlich

For what it is worth....Inhave a 1928 Dictator....and had the same problem of grinding gears when learning to drive my 85 year old car......learned to shift at lower speeds solved my problem for the most part.....found it starts out in 2nd or 3rd gear too.....my manual suggests one should be in 3rd gear at 10 mph.......no need to down shift most of the time as you can take most turns at 5-10 mph anyway......I'm 67 so have driven many manuals over my days....they are much different than my dictator. I do double clutch without thinking about it, and just slide into the next gear. It one's take practice to down shift without any noise.....hope this helps ...

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