using ATF in 944 trans with factory LSD

[roadsportusa]

I have a 1983 ,944 with manual trans and factory LSD

can I use auto trans fluid in this gearbox for race application?

[ernie9944]

Originally Posted by roadsportusa

I have a 1983 ,944 with manual trans and factory LSD

can I use auto trans fluid in this gearbox for race application?

NO____never heard of anybody using auto trans fluid in a 944 it will be suicide.Use only gear oil syntec either 80w90 or 75w90.The brand will be whatever you fancy, most owner will use (Red line -Swepco-Mobil ect )I will stay away from Royal Purple. And make sure it's compatible with your LSD.Some boys out there with racing experience will probably come on & guide you in.

[commdiver]

Swepco or Red-line 75w-90 should be used for great shift and extra protection!

I think you heard somewhere that ATF is used as an old manual transaxle and transmission cleaner fluid. You can warm up transaxle then drain transaxle fluid oil and then slightly overfill with ATF. Then rdive car gently on road for a few miles around town ONLY?

Then drain the ATF, as it has a huge amount of cleaning properties. Then you can re-fill with fresh gear oil!

[idontknow]

Ever heard of GM synchromesh fluid? It's not a standard gear oil and I can't vouch for it though it is compatible with the metal types in your transmission.

A friend of mine uses it in his turbo grand prix transmission and he's always raving about the stuff. I did look it up and seen it was being tried out in many different transmissions. Most with positive outcomes.

Pennzoil sells their own brand of the same stuff.

[_Van]

I believe you're only supposed to use GL4 with the LSD. Not the more common (and modern) GL5.

[RedBaron]

Use a GL4 rated fluid. I use Redline MT90 in my S2 box with LSD and it is fine.

Do not use swepco, as it is a GL5 fluid.

[billy mild]

Doesn't GL-5 cover GL-4 requirements?

[idontknow]

no, the formulation for gl-5 has properties that are harmful to your transmission.

[oliver88]

Use a GL-4 lube like Redline MT-90 or Amsoil MTG...GL-5 is really not ideal and may cause some synchro issues long term...Both Redline and Amsoil are easily obtainable and do make a difference in the shifting feel.

[HondaDustR]

While GL5 tends to be more agressive on brass syncros, it also generally offers more protection for the diff and final drive with its increased EP additives. It gets tricky that way since the box is a transaxle. Its your choice, and the red line/amsoil is good stuff. I use the Mobil1 Synthetic 75W-90 and have had good results. I like to drive it hard, but I also match all my shifts and rarely make the syncros work.

Here's a very good link to a gear lube lab study. Unfortunately, it does not include any GL4 spec lubes.
Royal Purple not so good? Gear Lube Study

[guru944]

Roadsportusa;

LoL, to Oliver 88 recommendations.

I use AMSOIL MTG in my S and it made a " World of a difference".

Later...

[guru944]

Opps!

This AMSOIL SEVERE GEAR is for your diff as well.

also use this in my S, Just love AMSOIL Products...

Later...

[romad]

Where do people hear these things....ATF is a hydraulic fluid with some lubricating properties. Can you imagine ATF in a manual tranny at race speeds....holy s...............!

[HondaDustR]

ATF is more or less 10 or 20 weight mineral oil with alot of detergents, anti-foaming, and other sorts of additives that make it also a good hydraulic fluid. Alot of other hydraulic fluids likely also are mineral based. It is too thin to protect under the loads encountered in a differential/final drive and lacks the EP additives, but there are "hydraulic fluids" that do. Alot of farm tractors run a common sump between the hydraulic systems and the gear case, including the final drive and differentials and require a whole lot of just one oil. The point is, it's all oil at the end of the day, just a matter of using what has been properly formulated for your given application.

Oh, and 80 weight gear oil sounds pretty thick, but it really isn't much thicker than 50 weight motor oil at operating temps. Just a random fact of the day.
Viscosity Charts

I second ATF as a fill for flushing the tranny out. Just drive it gently to get it warmed up.

[romad]

As with grades of oil for specific application its all in the design. The 944 manual trannies were not designed and tolerences for ATF's.

As for racing I would be more concerned about potential relibility issues it might present than what potential " miniscule" gains I might get from using a different oil.

Racing is 40% chassis set-up 20% driver, 20% engine and 20% pure luck. Reducing friction by .01% in the tranny is just not going to be your winning water shed.

And any thought of it in a street car is simply wrong.

[smokin_944]

Originally Posted by oliver88

Use a GL-4 lube like Redline MT-90 or Amsoil MTG...GL-5 is really not ideal and may cause some synchro issues long term...Both Redline and Amsoil are easily obtainable and do make a difference in the shifting feel.

I agree. I personally use Amsoil synthetic 75W90 and it is so far the best I've used. However, I have only driven 80,000 miles with the car so my experience is limited.

[Pete R]

Originally Posted by guru944

Roadsportusa;

LoL, to Oliver 88 recommendations.

I use AMSOIL MTG in my S and it made a " World of a difference".

Later...

What part? He's spot on. The problem is 944's and 928's have the tranny and diff sharing the same fluid. Gl-5 would be ideal for the diff but they are TOO SLIPPERY for the syncos to work well.

I have used both redline and Amsoil both are excellent and one offers no benefit over the other. and there are many others that will be adequate. I used to use a standard oil in my 928 and had cold shifting issues.. swithed to the Redline and I no longer had them.

[sasquatch]

Many new cars run ATF as a manual transmission fluid. My Mercedes Benz uses ATF in the transfer case as did my old 1989 full sized Bronco. We ran ATF in 2 stroke MX bike transmissions for years without a problem (KTM and Husqvarna).

I do not suggest it in the 944, but just wanted to say that other brands actually spec it.

[Slam]

I'm with the Amsoil guys on this one. Anything else would be like asking your car to drink vodka instead of schnapps...