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It depends how often you do this fluid change or gear oil. I just buy these pumps for $7/ea at Harbor Freight and chuck ‘em in the trash after. Worth it.
refills were 3.0 to 3.1 liters after draining 45 - 60 minutes
the aluminum seal ring (same one also used on GT3 engine oil drain plug and in some other Porsche engines) is present on fill plugs but I heard of a few that did not have it (manuals claim it is supposed to be on both fill and drain)
after you have gotten the fill plug off, and you don't put it on with too much torque, it will not be a problem to get off again (torque value is 22 lb-ft (30 N m) but most people don't have a torque wrench that will fit in filler plug area
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Last edited by enthusiast; Oct 27, 2021 at 09:25 PM.
Old thread, but figured it would make sense to keep all data in one thread for transmission fluid.
Blackstone analysis is common for engine oil, but has anyone run a Blackstone on their transmission fluid? Would be very interested to see some people starting to run analysis on their transmission fluid to build trends and help the community. I sent mine in, all came in within range outside of slightly elevated iron levels (silicon too, but expected). Surprising given that 6k miles ago while my transmission was out, I had it opened and confirmed that all internal components looked healthy, exhibiting little to no wear and I have no difficulty with the transmission shifting. My best guess is that their classification of "Transaxle Porsche" for the transmission is taking into account your standard C2S boxes, which are not like our motorsport derived boxes. There is typically quite a bit of material on the drain plug.
I reached out to Blackstone about my results because they originally had it listed as a Getrag 6 speed. They then changed it to be "Transaxle Porsche". They said:
The Getrag 6-speed averages aren't as well established as Porsche transaxle averages, so we'll keep the transmission logged in as a transaxle for now.
I updated the comments to discuss silicon and I sent you another copy of the report.
I wouldn't worry too much about the extra iron, especially because everything looked good when the transmission was opened. Silicon is from sealers so maybe some of the iron is from the inspection as well. Anytime a unit is opened for service or inspection, there's a chance we'll find metal and silicon, from parts getting reacquainted and sealers/gaskets. Let's just see where iron goes from here.
This report is from someone else, but interesting how they list the transmission type as something totally different and the average/normal iron levels match about what mine are: https://rennlist.com/forums/attachme...213d1720099156
I also do Blackstone analysis on transmission oil changes as well as engine , but have only done one for my GT3 since it's only had one transmission oil change :-) . I will dig it up, its been a few years and cannot remember what the baselines averages were from.
Anyone have a chance to send their trans fluid into Blackstone? If you haven’t, would be great to gather some additional data like we already have for our engines. Post up your report if you’d like.
Anyone have a chance to send their trans fluid into Blackstone? If you haven’t, would be great to gather some additional data like we already have for our engines. Post up your report if you’d like.
I sent mine in for analysis before I regear my transmission so I have a little bit of a baseline with the 4.00 R/P:
2800 miles on the oil and a bunch of autocross laps (>150) on it.
Last edited by 00 Scrub; Jul 28, 2025 at 11:03 PM.
I sent mine in for analysis before I regear my transmission so I have a little bit of a baseline with the 4.00 R/P:
2800 miles on the oil and a bunch of autocross laps (>150) on it.
Thanks so much! This is exactly what I needed to know and our Iron levels are very close to one another.
I may change trans fluid again this year and if I do, I may send it to the same place you did just to get similar data.
Excited to see how the internal of your trans looks too when you regear it. Will be following in your other thread.
The silicon in mine is expected as I had the transmission previously opened and all showed as healthy. The concern was the iron levels, but ours show as the same. I had 6k miles on mine. I also switched to Mobil this last change.
I change mine every 10-12 full days on track. I don't even count the street miles.
If you only drive on the street, I'd change it every 2-4 years, assuming most owners here are barely putting 1-4k miles/year.
I change mine every 10-12 full days on track. I don't even count the street miles.
If you only drive on the street, I'd change it every 2-4 years, assuming most owners here are barely putting 1-4k miles/year.
The fluid that's used also factors into the equation. The Motuls I use should be swapped out yearly even without mileage.
The fluid that's used also factors into the equation. The Motuls I use should be swapped out yearly even without mileage.
Yep. I buy the bulk 20L containers of the Porsche spec Mobil PTX 75W90. I've tried every lube under the sun over the years for these cars, and end up using either Swepco 210/212 (GT4) or Mobilube PTX for my Porsche's.
When Motul's Competition/Gear 300 75W140 was out of stock last year, I switched to Swepco as they didn't have supply issues for their blue moly ingredients.
Thinking about trying Swepco 202 for the 997RS and see if it's happy with that.
