Never ending ? To use atf or gear oil?

[Jason5.0]

ok so im pulling my motor and have the tranny out and just kinda thinking ahead, im wondering which is really better? atf or the gear oil? a mechanic friend claims that ford said to use atf because it improves gas mileage slightly and makes it easier to shift in cold weather (thinner fluid), is it true or is it better to use the gear oil? the mechanic also claims the gear oil is better because it sticks to the gears better so heres the question.. which is really better, i have 3 quarts of each sitting in front of me, which do i put in?

i know its been asked a million times, but i cant seem to find a real anwser, which is really better, my fresh rebuilt t5 is on the line here (i know its still a pos tranny)

 

[Black 93 Fox]

I bought 3 quarts of full synthic ATF amsoil today. I like the ATF havent tried the gear oil.

 

[Jason 302]

Never put gear oil in a T-5, bottom line.

 

[HISSIN50]

If your NEW trans is a WC unit, run nothing but ATF IMHO! I would not even fathom gear oil in a WC box.

 

[gopher_6_9]

t5+gear oil = one screwed up paper weight.

Ford designed that trans to use ATF and gear oil will not lubricate it properly. I am going to use Mercon SP in mine.

 

[Daggar]

Never put gear oil in a T-5, bottom line.

Exactly! This isn't a hard concept to grasp. If it calls for ATF then you use ATF. I guess I just don't understand where the problem lies?

The ooooooooooold trannies used gear oil. Ours are not those trannies.

 

[bit]

Get a good lightweight gear oil in that trans and you will be a happier person. I know a lot of people are afraid to stray from what came in and people that don't know any better will make statements like those above. Get that ATF out of your trans and it will last longer and shift smoother. I run Redline Shockproof Lightweight gear oil in all my manuals.
-Brent

 

[89MustangGX]

I ran a nice Redline MTL (gear oil for manual tranny) in a T5 one time. That tranny actually lasted almost 7000 miles. That was without any racing of course, just daily driving.

 

[HISSIN50]

I am not sure that I would give a guy with a brand new trans advice to run anything but what is called for by the manual or builder/manufacturer.

 

[kslushy]

Your 1986 5.0 T5 will use gear oil. Thats what came in my old stock 86 as well, and I would not use anything else in it specifically.

 

[custom89stang]

simple. just listen to me. ATF, period. ATF, ATF, ATF, ATF, ATF.....Just did a swap to a t-5 today (well my mechanic, i helped and learned) and he put in ATF because he says it shifts smoother and is better for the tranny....so yeah

 

[HISSIN50]

I thought that '86 had WC T5's (ergo ATF).

 

[custom89stang]

a lot of these people here don't know what they are talking about. and if u really wanna dispute and argue that i will get my mechanic over here (who by the way was SELF TAUGHT) and owns a mystichrome cobra and a supercharged 347 stroker 5.0 and just did the swap on my car

 

[bit]

a lot of these people here don't know what they are talking about. and if u really wanna dispute and argue that i will get my mechanic over here (who by the way was SELF TAUGHT) and owns a mystichrome cobra and a supercharged 347 stroker 5.0 and just did the swap on my car

Exactly, I'm glad someone said it. But even with that most mechanics will blindly say put in it what it came with. There is no doubt the trans was designed to use a lightweight fluid. Inherent in the design are tight tolerance sliding surfaces that need a low viscosity oil to penetrate and lubricate. A thick 75w90 gear oil will NOT work for this. Now why was ATF used? It does the job, it’s cheap, and Ford was already buying tons of it for the autos. If you would like to continue to run it in your car do so, there is nothing wrong with it. On the other hand it you are like 90% of the people on this board and believe your car can be improved upon from its stock form then find something better. GM synchromesh is a great synthetic lightweight gear oil designed for their modern manuals. As I stated before Redline Shockproof Lightweight gear oil is also a great choose. As the guy above stated a lot of people in here don't know what they are talking about so don't take my word for it. Get on Redlines website and call them and talk to an applications engineer. Being an engineer myself I am willing to bet the farm he will tell you the Redline Shockproof Lightweight will work great for you.
-Brent

 

[Jason5.0]

ok so heavy oil is out 100% i think ill try and get some of that redline light oil and try it out just so my mechanic will shut up about the gear oil if nothing else... (btw my mechainc buddy doesnt touch my car he just makes suggestions and loans tools etc. i do ALL of my work myself with the occasional help from dad who is a diesel mechanic)

 

[maverick0716]

Your 1986 5.0 T5 will use gear oil. Thats what came in my old stock 86 as well, and I would not use anything else in it specifically.

No it didn't. All WC T-5 Transmissions (I believe it was 84+) use ATF in them. It's something to do with needle bearings and that they don't get lubricated at all if you use a thick oil.

 

[maverick0716]

I thought that '86 had WC T5's (ergo ATF).

......Concortedly the ATF will be a much better fluid to be placed in his transmission....Visa-Vi? lol (the "ergo" reminded me of the Matrix Reloaded)

 

[crazypete]

Dino 75w-90 Gear oil turned my moderately unshiftable T-5 into a completely unshiftable t-5. Ground every gear. Lucas garbage did the same.

ATF smoothed it back out. Actually.....I knew it was almost dead so I said oh to hell with it and did my trademark move: fill the case with silicone (tire spray).

It actually shifted _damn_ well for a while (I even got it into 5th!) then suddenly went downhill. So thinner fluids actually meant for gears will benefit shiftability.

 

[Stormwalker]

Does anyone remember the reason for not using the heavyweight oil? I think it has something to do with the little holes that it goes through or something, if you use a thick fluid, then it will not get through and lubricate things. So that is why ATF is used, but as people have already pointed out, gear oil will work if it is the same weight as the ATF (I just use ATF in mine, makes it simple). I wish I knew what to call the holes, it is hard to describe, and frustrating when you know what everything looks like but not the names of anything. Doo-hickey and gizamaroo probably won't work for technical terms.

 

[squeeeg]

Never put gear oil in a T-5, bottom line.

Exactly Correct