2300cc

Hello I was wondering if it would be worth changing the transaxle fluid in my 996. It is an 03 manual with 18k miles on it. I believe Porsche says it should be done at 90k, but is there an age recommendation on when to change it?

ivangene

it costs like nothing to do....and about no time...just change it - write it in the book

I would bet for ~$100 you are done

Macster

No change based on age that I know of. The transmission fluid doesn't get contaminated like engine oil so really the only factor in when to change it is miles.

I have had the transmission (5-speed in my 02 Boxster) fluid changed now more than a couple of times, the last time just a few K miles back. Cost of the fluid $48/liter (the tranny requires nearly 3 liters of fluid) and the labor was 0.3 hours. I think I got the car in/out of the dealer service department for under $250.

Might add the tranny is original and the car has nearly 250K miles on it.

I was talking to the techs about the tranny fluid change interval and the suggestion was if one wanted to have an early/preventative fluid change done a good interval would be say between 45K to 60K miles, something less than the 90K miles the owners manual gives.

The techs also pointed out that Porsche gives a 90K miles fluid change interval because Porsche has the confidence the fluid will last that many miles (at least). So there can be a case made that an early change, one done before 90K miles, really provides no or very little benefit.

Even so, I'm going to continue to have the tranny fluid in my Boxster changed every 60K miles or so until I get rid of the car.

For the Turbo, its tranny fluid is going to get changed soon. The original tranny was replaced at about 35K miles (due to a leaking selector shaft seal -- I might add the leak was spotted because I had the car in for an early tranny fluid change and the leak was spotted during this service and the transmission replaced under the car's CPO warranty) so the replacement tranny's fluid is coming up on the 45K miles. I think the next time I have the car in for an oil/filter service I'll have the tranny/diff fluids changed.

Sincerely,

Macster.

2300cc

Thanks for the response macster. It doesn't really sound like I should waste the money at the present time.

Gofishracing

Change your transmission fluid at least once yearly. Unlike heated engine oil it will retain moisture.

Topaz330ci

Once a year is overkill.

Change it every 30-50k with OEM fluid.

Oh and I had to edit my post - Drive it more!

Macster

Even with just 18K miles a fluid change would not be a total waste of money.

Check with your fave Porsche dealer service department using your car's VIN just to make sure there's no tranny fluid change due to age. I was basing my statements on what I recall from the owners manual, but sometimes Porsche issues bulletins that can override owners manual service intervals. The service department is the last word on what is required when.

Sincerely,

Macster.

Coujer

I just did mine in the c4... I did the the transmission with no problem very easy to do with the right tools but the front different story... the filler bolt is stuck and looks to be stripped so now looks like I'm going to have to take it to someone. Which is a bummer cause so far this car had been the easiest to work on.

2300cc

haha I will just change the transaxle fluid this winter. I'll be bored one day.Thanks for the replies!

Ubermensch

I changed mine at 90k miles and the sky didn't fall! With 18k miles I wouldn't bother. Once a year is just silly.

Tbred911

if your doing lots of track time you should change it every 8 track sessions... those gearboxes really heat up during track time and that degrades the fluid...

logray

I was researching this the other day.

Pelican seems to have the best price pretty much anywhere for the Porsche P/N (approved) shell transaxle manual gear oil, at about $14 per litre.

If you want to go with the Mobil 1 LS 75w90 which almost all parts shops carry, certainly you can find that for a few dollars less... but IIRC there remains to be a question whether that is an approved fluid or not.

Quadcammer

holy crap man, thats a hosing. Mobil Delvac, which is most likely superior to whatever porsche put in there (or at least the same) is like $45 a gallon.

$48 a liter is robbery.

Ubermensch

I don't have any question in my mind that Mobil 75W90 is not approved. I traded messages with their technical folks one day to get to the bottom of it. I ended up paying the piper at the dealership.

logray

Do you have any of those emails, it would be great to see them...

I've read some threads where people say it is the replacement without any supporting evidence, and who run the M1 product without problems, but others where it's not so clear and say they've had issues with it. I would steer clear of the off the shelf M1 LS 75w90 at most auto parts stores.

I just stick with the Porsche approved stuff and it works great for me... here are the Porsche approved MANUAL GEAR BOX P/N's for anyone who needs them (appx 2.7 litres required):

999-917-546-00 1 liter Shell Transaxle (whether it is true or not I've read that the Spriax stuff is a direct replacement, if you can find it... but be careful there are a ton of Spirax variants)

00004320420 Mobilube PTX 20 litres @ $700. Good luck finding this in smaller quantities.

I've also read that Mobil Delvac works.

From LN engineering's oil bible:

"What gear oil is best for my Porsche transaxle (manual gearbox)?

There are many excellent choices for gear lubes, both synthetic and non-synthetic that are appropriate for use in our transaxles. I have had excellent success with the tried and true Swepco 201 80W-90 gear oil everyone has been using for years, but many do seek the benefits of a synthetic hypoid or gear lube.

For transaxles that call for a GL-4 spec gear oil, I have had excellent results with Amsoil's fully synthetic GL-4 gear lube, not to be mistaken with a GL-5, which is "backwards compatible." Another excellent GL-4 is manufactured by Redline, MT-90, which is a true GL-4 75w90 gear oil.

For transaxles that are compatible with GL-5 spec gear lube, you have many choices. Swepco for starters, being the most popular choice for gear lube among most Porsche owners. Royal Purple makes an excellent Max Gear lubricant, which I have found to work well in worn transmissions that need extra cushion or have notchy shifting. I have also run Redline's 75w90NS in a 901-transaxle- this formulation does not have friction modifiers for limited slip differentials, which can be picky in some transmissions.

Another favorite of mine is Mobilube SHC 75w90 (now known as Delvac 1 75w90), not to be mistaken with the Mobil 1 gear lube found at your local flaps. This stuff is the factory GL-5 fill from Porsche in all their race cars and is an industry standard in semi / mixed fleets. You cannot go wrong with Mobilube SHC or its Delvac 1 branded replacement."

http://www.lnengineering.com/oil.html