Tranaxle oil

[markt944]

Going to change it, which one do u recomend?,and is it worth going over to sythetic?

Thanks Mark

[zedsn]

I ran synthetic 90w mobile in mine but there are different opinions on that as far as synthetis possibly being bad for the syncros. A valvoline synthetic blend might be the way to go. You will be getting a.few different opinions to this question though.

[bholmes]

You want to make sure to get the properly rated fluid, which I believe is GL-4 (double check me). GL-5, which is more prevelant also has addatives that over a long period of time can be corrosive to bronze parts, which are found in your transaxle such as synchronizers etc. I know alot of people have run the GL-5 fine and never really had any problem with it, but I personally use a GL-4 rated motorcycle hyphoid gear oil. I found it at the local motorcycle shop after not finding any GL-4 at walmart or autozone. That's just my opinion though. Keep us posted.

Also a side note, be prepared to battle with the allen head drain and fill plugs.

[johnnydee]

I notice that you are in the UK so that might make a difference to what product are available and what your car was delivered with. There are a lot of issues about friction additives that are relevant to the oil that you choose. For instance, the Red Line tech people tell me that Porsches are originally delivered with trans oil with 3% friction additives. U.S. trans oils are formulated with 6% slip additives. Replacing the oil with 6% slip formula can actually create issues with the synchros having too much slip and therefore not slowing things down enough to go to the next gear when downshifting and creating wear on the dog teeth.

I have been running Red Line 75W-90 in street and race cars for over 15 years and have been very happy with it. The only proviso would be that if you do run it, mix the 75W-90 and the 75W-90NS (the NS stands for Non Slip) and has no friction additives at all. This will give you the desired 3% level. The regular 75W-90 has 6% friction additives.

Just FYI, for all the 901 gearbox folks out there, Red Line recommends to use ONLY 75W-90NS in those boxes because of the synchro design in those boxes. Before anybody hammers me about this on the forums, I am aware that for cars with limited slip differentials, there is a tendency for the diff to be noisier in lower speed/tighter corners with lower or no friction additives but this is not bad for the diff. Red Line sells a small bottle of friction additives that you can use to add (sparingly) to the trans until it quiets down to your satisfaction. For race cars, this is obviously not a issue. I would say that going above 3% would not be necessary or advisable based upon what I have learned.

[Dantilla]

The 911 guys swear by Swepco 201. That's what I have in my 911, so that's what I have in the 944, too.

[markt944]

So what is it to be then the ?

The Porsche owners manual recomends{its an 89 S2)

Aprox 2.0 LT hypiod gear oil SAE80 API classification GL4{mil-L2105}

Clarks website says 2.6LT which is right ?or just fill till it overflows

I take it a GL4 with no slip is the best option but should that be semi synthetic, normal or full sythetic?

Thanks Mark

[johnnydee]

As I mentioned, we have been very happy with the Red Line in the racing applications and are also good with its use in street cars. The race boxes get taken apart once a year or so and we get to see how it works in tough environments. We are very happy with the product. Here are a couple of links from Red Line:

http://www.redlineoil.com/products_gearlubricants.asp?productID=38&subCategoryID=15&categoryID=6

http://www.redlineoil.com/products_gearlubricants.asp?categoryID=6

We are using the full synthetic. Again, I would think that if this is used on the street/track that a 3% friction modifier mixture might be best.

[markt944]

So then if i buy 1lt of ns and 1lt with slip then just add them together

is 2lt enough

Thanks again Mark

[johnnydee]

Yes, you are right. Just buy enough to mix half and half and end up with the correct quantity for your trans. Unfortunately, I don't know the correct amount but I am sure that 944 gurus on the forum can tell your right off the top of their heads. On the 901 and 915 boxes it is between 2.5 to 3 liters. I guess you might end up with a little extra if you are trying to hit the 3% ratio spot on. I would be tempted to use 1 liter of the regular and 2 liters of the NS giving you a 2% ratio. If you want to keep your options open, you could buy the above and the small bottle of the friction modifier to add a little if you get noise from the LSD. Doubtful though. 2% should be fine.

[markt944]

Ok thanks but the box n my S2 has not got an LSD according to the options sticker,not checked the car though yet

So would i be better off just sticking to all NS?

mark

[procon]

Originally Posted by Dantilla

The 911 guys swear by Swepco 201. That's what I have in my 911, so that's what I have in the 944, too.

+1
Good stuff!

[Aufenbahn]

Not to cause problems but my understanding is that the 911 tranny is a porsche tranny while the 944 tranny is an audi/vw design.

[markt944]

Cant seem to find swepco in the uk though!

[kdjones2000]

I recently changed mine. Went to Royal Purple 75W-90 synthetic, and seems to work very well.

Of course, the stuff that came out didn't look that bad either, even after 115k on the clock.....

Many use Redline or Sweepco. You will need 3 quarts to fill it up.

Cheers,

Keith

[procon]

Originally Posted by Aufenbahn

Not to cause problems but my understanding is that the 911 tranny is a porsche tranny while the 944 tranny is an audi/vw design.

The PO (RickV) told me to run Mobile 1 15W-50 & swepco 201, works for me.

[Scuba Steve]

I put in Mobil 1 75W-90 after someone on rennlist recommended it 4 years ago. It's worked out great.

[markt944]

Emailed Redline and this isthe answer i got

Hi Mark,



Thanks for the interest in our products- nice to see them in a “proper” car… I’ve had 3 Porsche 944’s and loved em all.



The product you need for your gearbox is Red Line MT90… This is a GL-4 rated oil specifically designed for transmissions and transaxles.

It will flow well when cold, and offer a constant viscosity as temperature changes.

This means it will always have the correct co-efficient of friction for your synchros and is non- corrosive



In summary it will…

Eliminate notchy shifting

Allow high-speed downshifting

Give excellent shifting even when cold

Eliminate gear whine & rattle at high temperatures.



Loads of dealers listed on the website depending on where you are based but a few suggestions are---

1.) Demon Tweeks… All our products in all catalogues and in showroom

2.) Porscheshop… Carry a small stock of our gear oils at all times

3.) Opie oils… offer a discount scheme to members of almost every UK car club



Any problems or questions just call me direct on the number below.



Kind regards,



Lee Rushton


So even though people recomend different makes /type etc ,i think i will stick to MT90

Mark

[bleu951]

I use the MT-90 and have been pleased with it. You will need a little over 2 quarts, so you have to buy three. Install 2.0 liters per the manual. There is a note in the shop manual that gives a height below the fill hole. I just install 2 liters and go on. I measured it once and it was correct with 2.

To install it, you can use a transfer pump, or buy a suitable length of hose and attach a funnel to it secured with a hose clamp. Remove the rear wheel and prepare to camp out for a while. This can be kind of messy, so prepare.

Remove the fill plug first, then remove the drain plug. You will need a 17mm allen wrench or the VW tool. Clean the plug first so you can get the socket in far enough not to strip and cause grief.

[Gary2397]

I used race proven products such as Royal Purple. This is the only gear oil I put on my 1983 944.

I used to put Red Line on my car , but I switched for some reasons.

[Keithr726]

I switched too redline Mt-90 a year ago and it no longer grinds going into 2nd when cold however it still does going into reverse when its near freezing.

Oh yeah, Napa auto parts sells redline products also.