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Mobilube PTX Transmission Fluid: "Must do maintenance" for all 997s
While I had my car on Wayne's lift the other day for the water pump project, I also changed my tranny fluid to PTX. Its one of the simplest DIY projects and based on my results I believe it's "must do maintenance" for all 997's - no matter what your milage is.
After seeing the black, stank oil that came out of my car...I 100% disagree with the Workshop Manual's 100k mile replacement cycle.
I wont do one of my overly detailed write-ups because there are a lot of write-ups and videos on how to change the fluid. However I did want to share my results.
The Symptoms:
Like all 997s, my transmission was sometimes stubborn getting into 1st and notchy in 2nd. Nothing severe, just a minor annoyance from time to time. It was more pronounced when I first bought the car because it hadn't been driven in a while.
However, over the past 6 months I started to hear a slight grind on my first shift of the day into 4th. Searching RL it looks like this is a common issue for 997s. If I shifted slower, or had my windows closed, I wouldn't hear it. I would always forget with the onramp calling me...
The Results:
First shift after changing the oil had a buttery feel. After a couple more shifts I didn't feel it anymore, but it's noticeable at first. What you will notice is its far smoother getting into 1st and 2nd. No stubborn shifts into 1st, no notchiness into 2nd.
As far as my issue getting into 4th, I was initially disappointed because it continued to grind for the first 1-2 drives. However after a few days it has disappeared completely. I assume it took a little while for the new oil to wash out the crud.
What You Need:
- 3 liters of Mobilube PTX ($100 at Suncoast).
- a transmission fluid pump from Harbor Freight ($9). I recommend this because its designed to grab on the fill hole threads so the hose doesn't fall out and make a mess.
Quick Tips:
- Remove the two rear underside panels
- Unscrew the fill hole completely before you remove the drain plug. It will flow better and wont splash everyone.
- Unscrew the B+ cable next to the fill hole to make it easier to get the socket on it
- You know its full when you start to see the oil drip out of the fill hole. It will lake 2.75 liters exactly
- For you fastidious ones, its the perfect opportunity to clean your underside panels while you wait for the fluid to drain.
- Also a good time to inspect your transmission mount and shift linkages.
Great DIY as always. Only thing I would add is that there is a second fill plug on the transaxle that is the INCORRECT fill plug. Fill the trans fluid through the fill plug that TheBruce correctly identifies in the post above. If you’re pumping in much more than 3.1 L, you’re in the wrong spot.
I had my tranny fluid changed after 30K miles. No reason to change fluid other than the car was at my indy for bi annual brake fluild flush and I asked to have it done. My trusted and highly regarded indy decided to use Rennline fluid that they use in their racecar builds. That was a mistake as I lost my previous smooth shifting. Immediately switched back to the same Mobilube PTX and smooth shifting returned. Mobillube is the only way to go.
As mentioned by Bruce, the factory service interval is 100,000 miles and my local Porsche dealer tech who I have used for over 30 years said it was, in their view, changing the tranny fluid is unnecessary at 30,000 miles. And the dealer does like to sell services (that are needed). I experienced no performance improvement over the original fluid that was in the car.
I understand preventive maintenance but in my case I had no significant issues before the change and should have waited.
I will add that the LN Engineering magnetic oil pan drain plug is the same spec as the manual transmission drain plug. When doing my PTX changes, I installed these in the bottom drain plug position to catch any renegade ferrous debris and keep it from circulating inside the transmission.
Fantastic video, thanks. I have exactly the same issue on my 06 with 58k miles. I had an 06 Cayman that shifted like a rifle action so I know its probably just a matter of taking up some wear. Good idea to change the fluid with PTX too.
Since this has popped up again I'll add my two cents ...
Make sure you can remove the fill plug before you attack the drain plug.
I follow the same procedure for a motor oil change. Make sure you can release the motor lid before ... especially important if you haven't rerouted your emergency release cable.
I've helped with this gear oil service on jack stands as well as the lift. I'm no longer willing to pull the bottom panels on jack stands. At the highest jack stand level that I feel is safely achievable my chest still drags against the undercarriage. Getting those panels back on sucks!!!
Jim ... If you're reading this we might want to do this service when we'll have the lower panels off.
Also ... Those cheap pumps are generally good for one use. Pick up a couple at a time so you're prepared for the next time!!!
Aisin is the supplier. Has been for a while.... not all Porsche models, but many. I suspect Porsche saw the manual transmission as a sunset item and got out of the business.
01-12-2019, 09:42 PM
Mobilube PTX Transmission Fluid: "Must do maintenance" for all 997s
- Thx for the heads up.
