Transmission and Differential fluid change

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Neo1967

Neo1967

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I have two cars with the ZF 8HP; I spoke with a ZF tech and he recommended changing the ATF at 60k miles. I'd definitely change the diff oil at the same time.
Thanks!
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TimM.

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Regarding the rear diff... I changed mine at 5,000 miles. In that 5k miles I did a total of 4.25 hrs of hard tracking at Sonoma Raceway and the remaining street time was probably 70% hard driving through twisty canyon roads and all of it was during cool outside temps. My previous experience with tracking the S2000 being hard on diff oil motivated me to see how the A90 diff oil was holding up.

So how did the diff oil look? It was probably fine for a couple more track days and hard street driving during these mild months but I'm glad I checked. First, the oil level appeared to be lower than I expected from the edge of the fill port. Second, the oil that I extracted was pretty dark and shimmered with fine metallic particles but it didn't smell burnt and seemed to be in good condition otherwise. I extracted as much oil as I could and filled the diff with Royal Purple 75W-90 until it overflowed and proceeded to Laguna Seca 2 days later. I plan to inspect it again in roughly 5K miles to see how it looks.

I also plan to drain and fill the transmission before my next track day on March 27th. I use Bimmerlink to monitor all my fluid temps but the diff temp sensor is not available to the Bimmerlink app for some reason. The transmission temp is available but seems to max out at 199 degrees fahrenheit. Maybe it really is only reaching 199 degrees but it stays pegged there through about 50% of the track session and quickly dips below 199 on the cool down so I not too worried.

Any track junkies changed your trans fluid yet and have any feedback? -Thanks
 
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Neo1967

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Anyone have any D.I.Y. write up with pictures they could post on transmission and differential fluid change?
 

reyes.chester79

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reyes.chester79

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RenRed2

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The technical data for the ZF8 is 90000km's service - oil/fluid change. So about 60000 miles. I did mine on my M235i at 100000km's. The fluid was in good shape overall. NO refuse or issues with material in the gearbox pan.

Changing early is not worth it or required. My M235i was a daily in Germany for almost 5 years. Alot of fun time on the Autobahn near my place and in the hills on the fun dynamic roads.

Remember this gearbox has been raced. Not many will exceed its capability. Its strong.
 

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The technical data for the ZF8 is 90000km's service - oil/fluid change. So about 60000 miles. I did mine on my M235i at 100000km's. The fluid was in good shape overall. NO refuse or issues with material in the gearbox pan.

Changing early is not worth it or required. My M235i was a daily in Germany for almost 5 years.
@RenRed2, most advice for transmission service goes by mileage, but what is your take on a time based interval? I typically go with 4 years for transmission oil change, cos my cars tend to be low mileage. But I don’t think it was based on official ZF advice…
 

RenRed2

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@RenRed2, most advice for transmission service goes by mileage, but what is your take on a time based interval? I typically go with 4 years for transmission oil change, cos my cars tend to be low mileage. But I don’t think it was based on official ZF advice…
I changed mine based on useage. My dealer and his ZF contacts had no issues with that. I think the only real issues is the cost of the ZF fluid lol. Useage should be no issue unless you let the car sit for a long time. I saw nothing in my ZF data referenced to time.
 

Motorknut

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I changed mine based on useage. My dealer and his ZF contacts had no issues with that. I think the only real issues is the cost of the ZF fluid lol. Useage should be no issue unless you let the car sit for a long time. I saw nothing in my ZF data referenced to time.

i just can’t totally believe that oil left in use for ten years would still be in prime condition, despite low mileage use. In the sense that it should likely deteriorate with time, as most oils would. The climate where I am is also hot and humid.

That said, the BMW dealer has never mandated transmission oil changes in my experience, I always did it out of pocket. But ive heard that the Toyota dealer here includes it for the Supra’s second scheduled full service. I’ll have to see what they say when it’s time for mine.
 

RenRed2

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RenRed2

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i just can’t totally believe that oil left in use for ten years would still be in prime condition, despite low mileage use. In the sense that it should likely deteriorate with time, as most oils would. The climate where I am is also hot and humid.

That said, the BMW dealer has never mandated transmission oil changes in my experience, I always did it out of pocket. But ive heard that the Toyota dealer here includes it for the Supra’s second scheduled full service. I’ll have to see what they say when it’s time for mine.
I follow the ZF guidance and a dose of COMMON Sense lol. 10 years yes thats a bit much. But if a car sits a few month etc thats not the end of the world 4 or 5 years is reasonable schedule. I was driving everyday the M235i, so useage was driving the decision.
 

Motorknut

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I follow the ZF guidance and a dose of COMMON Sense lol. 10 years yes thats a bit much. But if a car sits a few month etc thats not the end of the world 4 or 5 years is reasonable schedule. I was driving everyday the M235i, so useage was driving the decision.
Yeah, well that’s kinda my point around time based interval advice. Cos bmw calls it “lifetime fill”, but 100k miles or 10 years later, it’s not their problem anymore.

I find it interesting that Toyota has a different approach to BMW on scheduled service - the 2000km oil change, now transmission & diff fluid service too. But it does make sense to me.
 
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