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As the title states, I'm curious as to what you guys run in your 3 speed trannys. The ford manual calls for SAE 50, but also lists SAE 90 as an alternative. While searching the forums and google, I see various opinions on what to use, but the common factor I see is to not use synthetic oil. What do you run in your 3 spd?
My 4-speed requires the same - 50w motor oil or 80-90w gear oil. I was so proud of it after it was rebuilt I splurged on synthetic gear oil, which wept past the new seals. I replaced it with 50w dino oil and all is fine. Big difference in price too.
Eric
I've currently got some 80w90 leftover from flushing my differential, but I would need to buy more as I don't have enough left to completely fill the trans. I know you said you used the 50w dino with success, but is one of the two more preferred over the other (between 50w and 90w)? If I've got to buy new fluid anyways, I'd prefer get whichever is best. Maybe it doesn't make a difference between the two, but was just curious.
There is (some) concern with hypoid gear oil additives included in modern 80/90 causing corrosion to brass gearbox synchros. It's designed for differentials, not transmission gearboxes. A straight weight 50 mineral is a good choice. I can say though if 80/90 does cause any trouble it must take a long, long time.
Sounds good, I think I'll got 50 to play it safe with my luck. Im assume just straight 50w with no additives or anything special, right? I assume detergent free?
Perfect, thanks everyone. I went with the Valvoline 50w. Oddly enough, the owner's manual I have for the truck calls for 3.5 qts in the transmission, however I was only able to put about 1.75 qts back in. This is also about the amount that came out when I drained it as well. Is the 1.75 qts approximately the correct amount? I dont see any other fill plugs that would allow me to put more in, so I assume the 3.5 qts is a typo in the manual (or possibly referring to a different trans all-together).
Fellas,
For what it is worth: I to recall the talk about some gear lube additives being tough on the brass parts in the manual transmissions. Rear differentials, transfer cases were not an issue - no brass parts.
The SAE 75W / 90W GL-5 gear lubricant was claimed to be the lube type that was tough on brass shifting syncros.... so some guys would use 75W / 90W GL-4 gear lube, did not contain the brass-eating additive.
Fellas,
For what it is worth: I to recall the talk about some gear lube additives being tough on the brass parts in the manual transmissions.
Yep. Waaay back in post #4, although I'm sure it probably is an issue, I've been using 80w/90 gear oil for 20 years and the transmission still works fine as far as I can tell. The 3.03 is pretty dang tough!
I was talking to my amsoil guy about my 3 speed. He said they got a gl-4 equivalent that he uses in his Chevy that has brass synchros. Not the cheapest but it’s amsoil so good stuff.
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