Porsche PDK clutch fluid and final drive gear oil change, on 991.1 

Thanks for your comments. Good luck with your PDK maintenance. My biggest lesson learned was to pretreat the aluminum bolts for the pan with penetrating fluid before trying to remove them. They are really soft and break easy.

Thanks for your comments, I really appreciate that.

Glad the video helped. You might also look for Jeff Richardson on RU-vid. He has some great Porsche maintenance info.

Thanks for the comment. Glad the video was of interest.

Your welcome, thanks for commenting.

The final drive and clutch oil do not share the same reservoir. That is why they have separate fill and drain plugs.👍

I have an 11' 3" ceiling height. I paid $3700 for the lift and installed it myself. I really like having a lift, I wish i had gotten one sooner. I'm not sure mine is better than any other, so I'd rather not make a recommendation.

...rear...

Thanks for your comments. Yes, there are two oil cavities and thus two drain screws. The Porsche service manual says to drain them both. For your second question, refilling exactly what you removed should be good enough, assuming you had the correct level when you started. The Porsche service manual has a few different procedures that I combined for simplicity. Checking and topping up the fluid with temperature consideration after the drain ensures you have the proper level. The measurement of what you took out is my preference and not part of the Porsche process. I hope this helps 👍

Thanks Jack! 😊

Porsche changes the filter at each service interval. My 991.1 Porsche schedule says 10 years or 100k miles, whichever is first. I personally would change the fluid every 50k or 5 years, but I wouldn't change the filter until the Porsche service interval.

@@jackharding98 Thanks!

I do mention both fill plugs for the PDK in the video. There is 1 final drive gear oil filler plug on the passenger side per Porsche procedure WM399055, and there is another filler plug for the ATF/clutch oil on the driverside per procedure WM370255. 👍

Thanks for your comments. I have not yet serviced the PDCC (Porsche Dynamic Chassis Control) or AOS (Air Oil Separator). The scan tool I have is an older Autel MD808PRO. I used it to get the PDK temperature. I'd prefer to have one of the newer Autel tablets, but my old unit keeps doing what I need.

@@jackharding98 Thank you for your reply. I think a lot of people would benefit from a video on the PDCC & AOS as there aren't very many videos on it...at least not on the 911 991.1 anyway. I'm looking at the iCarsoft scan tool, but will check out the Autel as well. Thanks again for all you do, people do benefit from your videos for sure especially since you explain what you're doing and give the why behind the what.

@wwilliams1358 Thanks for the encouraging words and the request on PDCC & AOS. I'm putting an instruction sheet together for myself on the PDCC right now. The reservoir should be replaced every 6 years or 60K miles, so I'm due for maintenance. I'll put a video together when I do the work.

@@jackharding98 I will definitely be watching for it. I'm not sure if mine is due since I purchased it in May 2023 as a CPO, but I'm not certain what they did. I currently have 68K on the clock however, no messages...yet! Thanks again for all you do for the 991.1 owners!

I did not "recalibrate " anything. My copy of the Porsche service instructions do not list a recalibration. Do you know of something specific that needs calibration? Please share.

It calibrates given current state of wear on clutches. Makes shifting smoother and more precise and reduces wear going forward. Not sure off the interval period. It will function fine without it…

​@@bfruehauf427 Are you able to share where you learned this information, are you sure it relates to the 991? I see nothing in the Porsche workshop manual regarding a calibration for the clutch disks or during a filter & fluid replacement. There is a procedure WM373427 when replacing the trans or after major repair. There is also a WM373055 after replacing the Trans, Control Unit. Both of those mention a calibration, but no calibration procedure is mentioned for a fluid & filter service. I like to learn and share info, so I'm curious.

The Porsche service procedure does specify connecting PIWIS and activating fill mode. However, in a drain and fill, you aren't fully draining the valve body, so there isn't a need to do that. RU-vid Jeff Richardson demonstrates this in his video. I didn't activate fill mode, and I haven't had any issues.

@@jackharding98 Thanks Jack. I'm good with DIY's and your video confirms it can be done without special Porsche tools or paying the outrageous prices to have it done at a stealership or indy shop.

Thanks for the video. I’m about to do this myself and bought the tool to put the PDK in the fill mode. Why do you think the Porsche service manual says to go through a very detailed temperature based procedure and activate the fill mode if it’s unnecessary? From what I saw in your video it looked like you were short of what they claim the fluid capacity is? Is that correct? Thanks again.

@kevinw2331 Good questions, I'm happy to answer. Temperature of the fluid does matter because it impacts the volume of the fluid (it expands when hot). I followed the Porsche guidance on this aspect, but I used a simple Autel scan tool to get the transmission temperature via the sensor in my 991.1. The fill mode is designed to ensure the valve body is full and that the transmission cooling valve is in a desired position. I've forgotten the details that Jeff Richardson explains in his video on the fill mode, but the takeaway message is that he demonstrates that the fill mode isn't required on a simple drain and fill. I'm sure you would find his video of Value to watch it yourself. Just search his name and Pdk to find it. As for fluid level, I very carefully measured that I was at a correct level before I drained my fluid. Then, I carefully measured what came out of my PDK. I then ensured I replaced the same quantity of fluid while following the Porsche fluid level check process when I was complete. That's how I know I got the refill correct. Keep in mind that not all fluid comes out in a drain. Some amount is still in the transmission, and that's why total dry capacity is different than a refill capacity.

Thanks for the reply. I would have thought the Porsche engineers would know all of these basic items when they wrote the service manual. I also have the Autel tool that will put the PDK transmission in the fill mode and plan to use it based on what I’ve read from others. I don’t have the actual capacities in front of me but if you remove 4.5L and fill 4.5L that’s a good start but if the actual capacity is 6L than you’ve changed most of the fluid but not all of it. That’s mixing a fair amount of contaminant back into fresh fluids.. The stuff I’ve read from others that did put the PDK in the fill mode indicated that the transmission gulped another ~0.5L or so after doing that. Which makes me wonder did they somehow drain more than others? I should be doing mine in the next 30-40 days and I can report back on what I find. I plan on letting the system drain for a long time. My guess, for the street driving, not putting the PDK in the fill mode may be ok. For me, if I’m paying all the money for the fluids and materials I’d like to get closer to 100% of the fluids out and then back in. Thanks again for the debate.

Yes, I drained both fluids in the transmission and replaced the filter. I took a video of that, but I felt the video was too long, so I didn't post it.

The 997 and 991.1 share 2012 as a production year. The 991.1 was introduced in 2012, that's the reason for the title.

@bigpapa8635 I'm not sure I understand your question. Maybe some weird autocorrect happening in your post? Your engine oil drain and engine oil filter are not associated with under body covers. So there isn't any extra benefit to combining engine oil change and transmission fluid change at the same time. I'd do those tasks separately so that I could keep my workload simplified.

I just went to reply to this and saw that for some reason RU-vid made my reply like 30 times. Gotta love technology. Yes that answers my question that the two are in different spots and does not save time to do them at the same time.thx