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proper oil for bw overdrive

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auag85201 View Drop Down
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    Posted: Jan/24/2018 at 1:00am
i read in the overdrive manual that the only oil you can use in the bw overdrive is gl1 gear oil..but according to the tech service manual you can use 80 w. gear oil...10w 30 engine oil or atf type A...what do you guys use in your overdrive transmissions?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 8:41am
I used 70W80 (or was it 75W85?) or something similar in the first I had, used 10W40 synthetic motor oil in the last one, which was rebuilt. I wouldn't use ATF -- it's just too thin for my comfort. Modern gear oil isn't suitable for anything with brass or bronze parts, that's why I used synthetic engine oil. Synthetic because it breaks down less and lasts longer. 
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lyle Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 1:33pm
Frank is correct on all counts. The high mileage synthetic motor oils have higher gear shear and pressure rating usually. Look for a Cx-4 or GF-5 on the label.
I see that Castrol 10W40 high mileage is GF-5.
Don't get confused by SAE viscosity numbers for motor oil vs gear oil. 75 gear is similar to 10 motor and 90 gear is close to 50 motor. Two different systems.
Gear oil does not have detergents or other combustion related additives.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6768rogues Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 8:02pm
I put 80/90 gear oil in mine 35,000 miles ago and it works perfectly.
Why Ramblers? Chicks dig 'em. Whatever it is, I can take it apart.
Located near Rochester, NY
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 11:39pm
as above. it's not that fussy. i experimented with lighter oils (10w30) ended up with 90 weight gear oil.

as mentioned some have additives that eat bronze -- but careful reading reveals that that corrosion is very slow! i wouldn't use it, but it's not immediately fatal.

50 weight motor oil or 85w90, the old fashioned stuff is more than adequate. if you were to change it on a 10 year schedule you'd be insanely ahead of the game :-)

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T5z, 3.42:1 mustang axle
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mr_AMC Quote  Post ReplyReply Direct Link To This Post Posted: Mar/13/2018 at 11:44am
SO?? I just got a Twin stick car.. From reading .. Guessing that there is bronze in the OD unit??   Best oil to use would be????? Do synthetics NOT have the bronze corroding additive??
Thanks..
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Mar/14/2018 at 12:52am
it's nearly a religious question... lol...

i used all sorts of stuff, 80/90 gear oil seems as good as anything. i used 20W50 motor oil, that was fine. 

you should avoid the most common stuff, GL3 rated or whatever, that is claimed to eat bronze. i'm sure it's true, but it will take a loooong time to eat it.

the lube in these old style transmissions almost doesn't matter. it's just a not very demanding application. it's not under tremendous sliding forces, it doesn't get very hot, little chance for contamination, etc. i think this is why there's not some great do or die decision here.

since it doesn't get very hot, variable viscosity oils like 20W-50 don't get much thinner while operating.

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T5z, 3.42:1 mustang axle
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Mar/14/2018 at 12:26pm
Be careful - AMC changed specs on their transmissions several times as far as fluid. 
The real changes came in the 1980s with the T5 etc. - 
The best one I have used and I've tried almost everything over the years, is "Synchromesh" by Penzoil.
It's made specifically for the bronz or "yellow metal" containing transmissions and it made my T5 purr like a kitten and shift super-nice even in sub-zero temps. It holds it's properties and works great with synchronizers and it actually follows the AMC spec they last issued - which MOPAR continued to use. 
It matches up with what AMC recommended in the end. 
No ATF - I'd never use that i any transmission.
Yes, transfer cases do use it and that's just fine - there's no synchronizers like the transmissions use - they are different animals and go fine with ATF.
Some sites even rebuilder sites have said "10w40" etc but been there tried that. Eve AMC DROPPED THAT as a spec in later years. 

Actually it doesn't take forever to eat the bronze - that's how it's known - people tried it when it came out and it wasn't too long.........

I started rebuilding transmission at about age 15 - first, by necessity - I ate three of them racing my old Rambler. 

When you've seen as many transmissions destroyed and had the shifting experiences - and have tried several different things in the same exact transmission - I can say honestly I've done side-by-side comparisons over the years, changing fluid every few months to something different until I settled on the "Synchromesh" fluid-  and did the research on all the AMC technical service bulletins.

Do what you want,, but those synchronizers do go through heck....... and I never had as much great luck with anything else. 
I've used AFT, gear lube, several different engine oils including 50 weight racing oil and more..... and I'll never switch back to any of those ever again after the great experience I get with the AMC recommended fluid. (they called it "fish oil" because the AMC formulation stunk like heck)
I drive in temps from sub-zero to over 100 degrees - in town stop and go with tons of up and down shifting, and long highway drives. 

My Eagle gets hammered pretty hard - I am not easy on that transmission - and like I said, I tore up my first Rambler transmission three times in short order.... 

You'll get arguments back and forth - sort of like engine oil. But in this case it's based on real-world making a living at it and doing the research AMC did...... I spent months researching their documents, etc.

Just don't eat any yellow metal and do what makes it smooth and quiet........ your choice, your car.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Mar/15/2018 at 6:21am
I agree with you Bill.. and Tom. The newer trannys like even the T-150 are under more stress than something like the old T-96. More power going through them and modern drivers are harder on transmissions. I'd use motor oil before ATF -- nothing that thin should be in something that is splash lubricated like a manual trans! It's different in an auto with forced lubrication and less stress on the gears (no sliding parts, and smaller gears that spread the load more). Transfer case is a chain with the lower parts always in oil. The older all gear drive transfer cases used a heavier oil. I ran 10W30 synthetic in my T-96/OD and never had an issue. It did lunch the synchros early, but more because it had a 4.6L ~250 hp stroker in front of it than anything else... The synchros in that trans are a type that don't tolerate a lot of abuse or power, and I was putting 2.5x the power of a 195.6 OHV/2V (rated 135 hp gross, which equates to ~97 hp net... 72+ ratings  are net). Almost 2x as much even with the gross ratings...
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Mar/15/2018 at 11:47pm
thanks billd for the info. i'll go with your experience.

i was talking only about the old T96 of course, not anything more modern.


1961 roadster american
195.6 OHV, modded
T5z, 3.42:1 mustang axle
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