Click on image for the lowdown. 
====
| | | Forums66 Topics128,108 Posts1,056,568 Members48,448 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Sep 2006 Posts: 7 'Bolter | | 'Bolter Joined: Sep 2006 Posts: 7 | I’m looking for thoughts on manual transmission gear oil. I have a 59 GMC with a four speed manual transmission. In looking on line I understand GL-4 oils should be used rather than G-5 to avoid corrosive aspects of certain GL-5 oils. One apparent popular gear oil is Sta Lube gear oil, which is available at my local NAPA but it seems pretty pricy at $75.99 a gallon. https://www.napaonline.com/en/search?text=Sta%20lube%20&referer=v2Does anyone have other less pricy recommendations? Thanks for your help and guidance. | | | | | Joined: Oct 2021 Posts: 6,888 'Bolter | | 'Bolter Joined: Oct 2021 Posts: 6,888 | What does the shop manual call for? If it's the same as AD trucks, use 90 weight mineral oil for Ford tractor transmissions.
Available at Tractor Supply.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
| | | | | Joined: Jan 2022 Posts: 2,476 'Bolter | | 'Bolter Joined: Jan 2022 Posts: 2,476 | I've been using 90w GL-3 in my '52 GMC with the same SM-420 transmission as your '59 for 45,000+ miles. No telling what was in it when I got it. Autozone has it for $11/qt.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
| | | | | Joined: Sep 2019 Posts: 162 'Bolter | | 'Bolter Joined: Sep 2019 Posts: 162 | I use the “Travelers” Brand for ford tractor transmissions available at Tractor Supply and it is reasonably priced. Same as previously mentioned. Sta-Lube is too pricey. I have used it also in the past, so I believe it is a good product but the other is easier on my wallet. I believe it is sold in 2 gallon containers. Just don’t tell your GM products what is is made for and they won’t know the difference.
I invest my money in precious metals, mostly rust!
| | | | | Joined: Jan 2002 Posts: 2,842 'Bolter | | 'Bolter Joined: Jan 2002 Posts: 2,842 | I use NAPA Sae Mineral Gear oil 90W. Sells for $56.99 / gal.
Craig My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear My truck ....... Respect The Rust If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.
| | | | | Joined: Feb 2016 Posts: 1,991 'Bolter | | 'Bolter Joined: Feb 2016 Posts: 1,991 | Go to the Valvoline site, manual transmission lube.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
| | | | | Joined: Sep 2006 Posts: 7 'Bolter | | 'Bolter Joined: Sep 2006 Posts: 7 | Wow, thanks for all of these suggestions. I’ll see which one is easiest to get locally. This is very helpful and much appreciated. | | | | | Joined: Sep 2006 Posts: 7 'Bolter | | 'Bolter Joined: Sep 2006 Posts: 7 | FYI, I ended up going with the “Travelers” brand from Tractor Supply. It was available locally and priced well. So far so good. Thanks again for all of the great suggestions! Much appreciated! | | |
|
|
