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Gear oils that meet GL-5 standard are often said to be GL-4 compliant, as this oil says on the label.
Using this gear oil might not harm your tranny, but it is probably not the best choice.
GL-5 spec oils are often found to be too 'slippery' to permit old, worn syncros to function to the best of their ability.
Sta-Lube, Red Line, and others still sell straight GL-4 gear oils.
Where I live, here in the west, I can get 5 gallon pails of Arizona/Colorado Petroleum straight GL-4 gear oil, and that's what I use in my syncromesh trannys.
GL-5 oils are certainly better than GL-4 oils in hypoid gear differentials though, where there is more sliding gear friction than there is in transmissions.
Last edited by millball; Apr 11, 2023 at 10:24 AM.
I'd use the GL rating and weight as specified by Toyota. Then there is no issues nor any need to try to improve Toyota specs. Changing the lube oil on schedule is the key and Valvoline makes a good oil. I change lube oil every 100K miles on my 86 2WD (482K miles) 5-speed and differential. Still original that shifts great with no issues nor leaks.
Gear oils that meet GL-5 standard are often said to be GL-4 compliant, as this oil says on the label.
Using this gear oil might not harm your tranny, but it is probably not the best choice.
GL-5 spec oils are often found to be too 'slippery' to permit old, worn syncros to function to the best of their ability.
Sta-Lube, Red Line, and others still sell straight GL-4 gear oils.
Where I live, here in the west, I can get 5 gallon pails of Arizona/Colorado Petroleum straight GL-4 gear oil, and that's what I use in my syncromesh trannys.
GL-5 oils are certainly better than GL-4 oils in hypoid gear differentials though, where there is more sliding gear friction than there is in transmissions.
I've heard good stuff about the Redline oil.
Where do you get your oil from? I live in southern AZ.
GL-4 only. A higher number isn't better for your tranny (because of synchros). Redline is nice stuff, but basic dino oil is likely just fine as well. Me? It's so rare I'll change it that I'm a Redline kinda guy.
Apr 11, 2023 | 09:18 AM
