vrnkc

The owners manual states that the 997 manual transmission fluid needs to be changed at 120,000 miles. BMW's E 46 M3's have their first transmission oil and differential oil changed at 1200 miles to remove the initial "break-in" metal debris . What do you auto experts recommend for preventive maintenance of our transmission?

Edgy01

I go by Porsche's recommendation. To do it early is unnecessary.

David A

Every 30K miles is good.

MHC2S

Sorry to bring this post up from the dead, But I did a search and found nothing. Does anyone know what Brand of trans. fluid is recommended by Porsche to use in our 6-speed gear box's?? I have a 997.1 factory service tech manual it only states the amount of fluid, but not the brand? Trans. fluid quantity is 3.1 qts. trans. fluid change quantity is 2.8 qts. Only trans. fluid approved by Porsche is to be used. Now which fluids are approved

I have been using RedLine synthetic MTL and ATF in all my past and current cars, and it works just fine. I still would like to know what Porsche uses in these 6-speed gearbox's.

Edgy01

Assume it to be about 70 weight.

MHC2S

I'm sure your correct on the weight. The RedLine MTL that I have used in my past 5 and 6 speed gear box's was a SAE 70W80 weight ( API GL-4 gear oil). Now I would like to find out what brand of trans. fluid does Porsche use in our cars?

MHC2S

Interesting I just went to the RedLine web sit and they recommend 75W90NS GL-5 gear oil for Porsche's.

http://www.redlineoil.com/product.aspx?pid=47&pcid=7

I still would like to know what is in our 997's from the factory

cbzzoom

OEM is either Mobilube PTX or Shell Transaxle. Neither is available for direct purchase by consumers in the US. They are pretty close to 75W90 but not the same as normal 75W90 oils (I went and found the data sheets at some point and the viscosity at various temperatures is quite different).

see https://rennlist.com/forums/996-gt2-...l-for-gt3.html
for example. (though beware, GT3 transmission is not the same)

Easiest way to get the right stuff is to ask your dealer or get it from Sunset or Suncoast.

cbzzoom

Ooo ooo , I think I just figured out what the OEM fill is.

Check out the OEM "Shell Transaxle" data sheet here :

http://www.6speedonline.com/forums/9...-75w-90-a.html

Then check out the Shell Helix Racing 75W90 here :

http://www.shell-racing.com.au/shell..._gear_oil.html

exact same specs :

Viscosity Grade SAE 75W-90
Kinematic Viscosity @ 40°C 81 mm2/s
Kinematic Viscosity @ 100°C 14.9 mm2/s
Viscosity Index 194
Dynamic Viscosity @ –40°C 35,000 mPas
Density @ 15°C 876 kg/m3 3
Flash Point COC 206°C
Pour Point –48°C
Steel Corrosion DIN ISO7120A 0

MHC2S

Thanks for that link. I can see the GT3 guys being so concerned about this since a majority of those guys track their cars and change the fluids more often. I did find out the Redline 75W90NS gear oil is a direct replacement for Mobilube PTX which is not available in the US. I am going to call Redline as well as my local Porsche dealership to find out what is recommended on our 997's.

cbzzoom

And the Redline 75W90 NS is very close :

Kinematic Viscosity @ 40°C 95 mm2/s
Kinematic Viscosity @ 100°C 15.6 mm2/s
Viscosity Index 176
Dynamic Viscosity @ –40°C 40,000 mPas

But it's actually a little bit thicker at low temp, which is the opposite direction of what we need. I'd like something a tiny bit thinner at low temp but comparable at high temp.

BTW "Dynamic Viscosity" = "Brookfield Viscosity" , and 100 mPas = 1 Poise

edit : Red Line info is here : http://www.redlineoil.com/techinfo.aspx

cbzzoom

And for the record, the Mobilube PTX :

Kinematic Viscosity @ 40°C 77.2 mm2/s
Kinematic Viscosity @ 100°C 14.5 mm2/s
Viscosity Index 197
Dynamic Viscosity @ –40°C 20,000 mPas


If I have the history right, I believe Mobilube PTX was the original intended Porsche fill, but it was discontinued in the US (because it's super toxic or something), so Shell Transaxle took its place. It looks like PTX is in fact thinner at low temp.

Also for the record : Swepco 201, Mobil Delvac, and Mobilube SHC are all much thicker at low temp. Maybe interesting for race cars where you care most about high temp performance, but no good for street cars.

edit : Mobil info is here : http://www.exxonmobil.com/pdssearch/search.asp

MHC2S

Thanks for that info cbzzoom. I believe when I ask my dealership which oil they use I'm betting it will be the Shell Transaxle fluid since Mobilube PTX is not available in the USA.