A friend of mine was recently told by some guys on a mustang forum to use ATF instead of gear oil in his Manual transmission. I told him I'd never heard of that before. I was wondering if anybody else had?

I would think that the gear oil would perform better cold as well as hold up better when really hot.

It's about to get cold in a month or two and I'm waiting to see if it is hard to shift for him.

He races at the track alot, I dunno. Anyone have any solid reasons as to why you shouldn't do this? I would hate for him to mess up his tranny.

 

I would never try that! ATF doesn't offer the same or even similar lubrication of gear oil. I know the transfer case on my chevy truck takes atf, but its chain driven, so my guess is that it doesnt need as thick of lubricant.

 

A transmission shop owner I have known for 20 years said it's OK.

 

The first time that I went to change all the fluids in my '90 BMW 535i, I looked up all the fluid capacities and types in the owner's manual, and it called for 75-90 gear lube in the transmission.

Got my stuff together, and when I got underneath the car, I found a metal tag on the tranny saying to use ATF only. That stopped me dead in my tracks, since it looked like a factory tag. Thankfully, I hadn't drained the sucker, yet.

At my next opportunity, I talked to a BMW tech friend and confirmed that I could use ATF for smoother shifting and better cold weather shifting. That's what I've been doing in that car, ever since, and it's got over 215,000 miles on it, with no problems.

I haven't thought about using it in my truck, but I don't imagine it would be a problem, based on the experience with my car.

 

Hmmm. Well, I know in my dirtbike (two-stroke engine, separate transmission with wet clutch) I run ATF for the tranny and it works great. ATF is a little thinner than most gear oils so depending on the vehicle/temperatures, I would be hesitant of using gear oil.

 

I had an 89 5.0L Mustang and the manual specified ATF in the 5 speed tranny.

 

It depends on the tranny. Toyota told me to do it in my 85 celica, the syncros were going & it was a good fix. I asked them about it in my 85 truck & they recommeded against it - they said the thruck tranny was under more stress, etc. and would burn it outby lack of sufficient lubrication. So it really comes down to the tranny and the design of it. Some of the new toyota trannies take it and some don't - I wouldn't do it without more information on that peticular tranny.

 

Yeah, the T45 in my friends 98 Cobra comes with ATF from the factory.

 

I think most Fords and Mazdas do ask for ATF in the tranny (as stated in the owner's manuals.....most Mustangs, Explorers, etc use ATF in a manual tranny equipped vehicle)....if you put in gear oil by mistake you'll know it because it will shift like crap. That being said, I would never put in something completely different from what was called out in the owner's manual (ie ATF is not gear oil and vice versa). Stick to your owner's manual as a guide for what to be using. You may be able to substitute one for another, but you'll definately be in unchartered waters when you do. You can also move down in weight to 75W-90 or look into using synthetics to help with heat and better shifting. Many racers do use ATF in their gearboxes to make the shifts quicker, but there will also be increased tranny noise from doing so (not that it matters on the track) and you may see increased wear on bearings and gear surfaces as well if the tranny was not designed for ATF initially. Some of the trannys filled with motor oil (10W-30 or similar) may have a much easier time switching over to run ATF since the lubrication numbers are close but if your tranny runs a true gear oil, you probably should refill with the same thing even for track use.

 

Alot of the new manual trannies use ATF now, The gears being more precision, alot harder and better bearing design only need light lube and cooling, ATF also causes less drag, More performance and gasmilage.
If gearoil is used in a manual ATF trans it will lag hard and not do good for it.

 

HAd a 91 f150 302 5 speed that required sythetic atf

 

Yeah, I had an old ranger the previous owner made the mistake of putting gear oil in...Burnt out the bearings and now the truck whines at EVERY SPEED and EVERY GEAR except fourth. Go figure...manual trannie that takes ATF.

 

Did the power steering pump whine on yours? My ranger and every other moderatley old ford from the past 20 years has had a PS pump that makes all kinds of racket. It's not louder than my exaust now thank God.

 

I was always under the impression that ATF is more of a Detergent/solvent than it is a lubricant, unless it's in large quantities (i.e. automatic transmission/manual).. Also, I didn't think ATF broke down nearly as quick as regular/synthetic fluids, in terms of viscosity...

I own a Mustang, and have always needed Synthetic ATF..


JT

 

No, but I've heard that's a common problem on Fords...I think thats "normal."

 

Most manufacturers are going to using ATF for both autos and sticks. It's a lot easier to only have to stock one type of transmission fluid at the factory. Ford's been doing it for years, and it looks like others have started catching on.

 

my eclipse use to be really hard to get into gear when cold, and would grind from time to time so i mixed dexron 50:50 with 75w90 gear oil and it fixed it, i ran that mix for over 30,000 miles with no ill effects