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Getting ready for transmissions oil change....


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Before I start I would like to know if I got all the parts. Repair manual mention only one o-ring for the drain plug of the manual transmission which is part#900 123 118 30. That mean there are no seals on the fill port???Also there is no mention of any o-rings on the fill or drain port for the front wheel drive and could not see any in the parts catalog? Anybody got any experience with those transmissions servicing? Thanks a lot, J.P.



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Correct the manual transmission filling port has no seal other than the plug.

Also correct, no sealing rings on drain or filling ports for the front wheel drive.

I highly recommend only Porsche spec transmission oil - too many horror stories of problems with other oils..

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Thanks Loren... I am searching through the net about the oil . The repair manual mention Mobilube PTX 75W90 but I have found some info mentioning it is replaced by Delvac 75W90 gear oil. Can you confirm?

Some people have used non OEM gear oil and say they have not had problems; unfortunately, many that tried this ended up with multiple problems (noise, hard sifting, etc.). As soon as the non OEM fluid was drained and replaced with Porsche's product (which is fully synthetic and made to their unique specification), the problems all disappeared. We only use the OEM product, which we buy from Porsche, and have never had an issue with it. Some time back, I wrote to several of the larger oil manufacture's concerning substitutes, and the response were eye opening: The larger and more credible firms replied that the Porsche spec product is unusual, and they did not have a match for it. The smaller firms all claimed they had suitable products; only problem was they made the gear oils that caused the problems in my customer's cars that we had to drain out and replace.

As Loren stated, I would highly recommend only using the Porsche gear oil. At the end of the day, it is your car and you can use what you please, but there is only one product that we use.

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Thanks Loren... I am searching through the net about the oil . The repair manual mention Mobilube PTX 75W90 but I have found some info mentioning it is replaced by Delvac 75W90 gear oil. Can you confirm?

As far as I knew, the factory fill for the 996TT gearbox was Mobilube PTX synthetic and I didn't think that had changed......when I just had my gearbox fluid changed, this was what they used. If you can't find a 100% definitive statement about it being replaced from Porsche, I would call and talk to Stan at Gbox Monday morning and just double check what he recommends. He is the leading expert on this Getrag gearbox and has seen a ton of them come through his shop. Just to beat a dead horse and echo the two experts, Loren and JFP are absolutely correct that you want to use this gearbox oil and only this gearbox oil. A lot of fluids that are widely accepted elsewhere in the racing world (Red Line, Royal Purple) are big no-nos in this gearbox.


Also, if you do find that it has since been changed, please let us know!

Edited by Silver_TT
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Flip, one tip. Loosen the FILL plugs first. To make sure you can re-fill the system. Don't want to have the tranny drained, only to find out you can't break the fill plugs lose.

OK, second tip, for free! LOL. You can send your drained trans fluid sample out for a Blackstone UOA.....if you're into that data collection.

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