zimwiz Posted February 18, 2016 Share Posted February 18, 2016 Does anybody have any suggestions for gear oil on a series 90 granny? Is 600 weight a good idea? What about the differential? Link to comment Share on other sites More sharing options...
Mark Shaw Posted February 18, 2016 Share Posted February 18, 2016 I have used SAE250 in my 20s & 30s cars transmissions and rear ends. The heavy lube helps to speed up non-synchronized transmission shifting too. Link to comment Share on other sites More sharing options...
37buick Posted February 19, 2016 Share Posted February 19, 2016 I dont want to start any trouble here but what about the gl 5 factor harmful on bronze bushings ? I know its almost impossibleto get to a conclusion but I found some good explanation online that made me change my mind and I found gl3 at napa. Link to comment Share on other sites More sharing options...
Larry Schramm Posted February 19, 2016 Share Posted February 19, 2016 GL1 is what is used in the Ford Model N tractors I believe and it is just plain mineral oil. That would not harm bronze bushings, etc. Link to comment Share on other sites More sharing options...
Hubert_25-25 Posted February 19, 2016 Share Posted February 19, 2016 I have a 1922 Dodge touring that calls out 600W. It has the same style non synchro gearbox as in my 1925 Buick. I wanted to replace the transmission fluid with what was used in the past. I found the 600W so thick, that the transmission had an extremely hard time with shifting. So bad, that I had to start off in gear and let the clutch out, because it would not let you go into gear from a stand still. There was either so much drag that nothing slowed down to get the gears to engage, or more likely, that there is so much syrup, that the gears can not rotate fast enough when the teeth get near, and it just wants to grind going in. I can't imagine how thick this stuff would be in real cold weather. I did a lot of research (and there are also a lot of opinions). I drained it out and I put in "MT-90" made by Red Line synthetic. It is a manual transmission fluid. It is available many places, but I bought it off Amazon. It is an API GL-4 so it will not hurt any bronze/brass etc. It is SAE 75W90. No problem with seal leakage, and it really shifts well. I like having the added protection and longer life from a modern synthetic oil. For the rear axle, you can use just about anything. No brass/bronze here. I just use Castrol 80W-90. You could use 90W-140, and just about any brand would do. Best Regards,Hugh Link to comment Share on other sites More sharing options...
37buick Posted February 20, 2016 Share Posted February 20, 2016 I didnt Know about the rear not having any brass nor bronze !!!! thats good info Hugh , tx Tomorrow im going to check in my garage what is the one i got at napa and will post Link to comment Share on other sites More sharing options...
Hubert_25-25 Posted February 20, 2016 Share Posted February 20, 2016 (edited) The brass and bronze issues regarding using GL-4 vs GL-5 come into place with synchronizers in newer manual transmissions. They are usually a sintered metal actually, but have the brass and bronze particles in them. But you don't have any of this in your rear axle, The rear axle does have a hypoid gear, so you can use an EP gear oil (extreme pressure). All the bearings are steel ball or steel roller style. There are 2 notes in the maintenance manual for my 1925 Buick for the transmission. One says to change the trans oil twice a year. The other note says "A good grade of steam cylinder oil should be used, but at the beginning of the winter season it is advisable to thin the lubricant by adding a quantity of engine oil. " It does not say how much to add, but hints that you may not like 600W. In the differential section, it says "The old oil should be drained off, differential washed out with gasoline or kerosene and fresh oil introduced twice a season. Who has the time for this? My differential was already cleaned when I got my car, and the transmission was out, but when I pulled the top off my transmission, the oil was pretty mucky and looked like taking the valve cover off an old engine where the oil is all caked up inside. I would think that just about any gear oil today is far superior to what was available in the past. Edited February 21, 2016 by gr8success (see edit history) Link to comment Share on other sites More sharing options...
Bob Engle Posted February 20, 2016 Share Posted February 20, 2016 There are brass spherical shims in the differential of 32 Buicks. Bob Engle Link to comment Share on other sites More sharing options...
37buick Posted February 20, 2016 Share Posted February 20, 2016 Napa has Sta-Lube brand Hypoid SAE 85W90 gear oil API GL 4 wich is safe on brass and bronze , the yellow metals After reading all of the opinions online I finally came to agree that this is the best I found. . Link to comment Share on other sites More sharing options...
Hubert_25-25 Posted February 21, 2016 Share Posted February 21, 2016 I think you have a winner with the Sta-Lube GL-4 for the rear axle. Good to know about the brass shims in the later models, but shims fall into a different category as I understand, because they are not a friction part like the synchronizers. Link to comment Share on other sites More sharing options...
Bob Engle Posted February 21, 2016 Share Posted February 21, 2016 While I called them shims, they fit between the carrier housing and the the spur gears. They act as a thrust bearing when the spur gears turn. There are brass synchronizers in the the late 31 and all 32 transmissions. With GL4 and other non GL5 readily lubes available, why take the chance? Bob Engle Link to comment Share on other sites More sharing options...
Hubert_25-25 Posted February 21, 2016 Share Posted February 21, 2016 Bob,Agreed, and thanks for the knowledge on the internals of the 31 and 32 transmissions. Hugh Link to comment Share on other sites More sharing options...
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