3 speed transmission
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
For a 3 speed manual toploader? They spec'd SAE 50 mineral oil or SAE 90 gear oil "with no EP additives". At least, in the Operator's Manual in '64.
90 wt gear oil will work OK, but the modern GL-5 versions have EP additives to reduce wear in rear differentials (Where 80/90 is most often used) that are said not to play well with brass synchros found in manual gearboxes. It eats them up. It's also said to be maybe too "slippery" and not quite what is wanted for dependable shifts or somesuch. I dunno.
So you kind of have to hunt around a little bit for GL-4 SAE 90 gear oil or, something specifically tailored and sold for manual transmissions. Farm supply stores or better auto parts stores will have it. Gear oil has a different measurement for viscosity than straight mineral motor oil, an SAE 90 gear oil is roughly equal to an SAE 50 motor oil. Or you can install spendy Red Line synthetic. $17 a quart. It is good stuff though.
90 wt gear oil will work OK, but the modern GL-5 versions have EP additives to reduce wear in rear differentials (Where 80/90 is most often used) that are said not to play well with brass synchros found in manual gearboxes. It eats them up. It's also said to be maybe too "slippery" and not quite what is wanted for dependable shifts or somesuch. I dunno.
So you kind of have to hunt around a little bit for GL-4 SAE 90 gear oil or, something specifically tailored and sold for manual transmissions. Farm supply stores or better auto parts stores will have it. Gear oil has a different measurement for viscosity than straight mineral motor oil, an SAE 90 gear oil is roughly equal to an SAE 50 motor oil. Or you can install spendy Red Line synthetic. $17 a quart. It is good stuff though.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
I ran 80/90 gear oil for 20 years, if it does cause problems it must take a while.
The Ford toploaders are pretty tough, among the best transmissions ever made. Ford does specify "no EP additives" which may be a different issue than the stuff that is hard on brass synchros?
The Ford toploaders are pretty tough, among the best transmissions ever made. Ford does specify "no EP additives" which may be a different issue than the stuff that is hard on brass synchros?
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