[GPG]

according to the manual the transmission oil change interval is 100k miles. Anyone change their oil more frequently when towing? Time or mile based?

[Blueboxer]

I would call your service department, if I recall correctly, the ZHP 8 speed is a closed system and they don't recommend doing the fluid change at all. I few people will do it right before their warranty up, figuring if it goes, it will go then while it is under warranty, but whenever I asked for a transmission flush, I was always told it wasn't recommended.

[Di3s3l_Power]

I just got my '23 45e and I tow max 5,000 lbs camper and I do plan on changing the transmission fluid around 30k miles or a year before warranty expires.

Over time the oil will degrade due to heat cycles and can create build-ups

Car manufactures refer as "Lifetime oil" as expected life time of vehicle & transmission (100k miles / 10 years)

I can't find the video, but I remember watching the ZF OEM Transmission Manufacturer disagreeing with lifetime oil but BMW and other car manufactures usually say lifetime.
What's the worst can happen? transmission fails outside the warranty and you either replace the transmission or buy a new car

[Blueboxer]

My mechanic offered to change it right before the warranty was up, he said in his experience it will fail soon after the change or not at all so if you don’t mind paying for the expensive transmission oil, go for it. 👍🏼

[Bking60]

Seems to be confusion between flushing or just the filter, clean magnets and top off. Never flush one. The equipment is usually contaminated. If you see brown fluid the transmission needs a rebuild. Its best to do your own filter because one bit of debris in there will likely kill it. This is why there is no dip stick.

[clutchless]

I will change mine at around 50,000 miles as recommended by ZF (as stated in the video) if I still own it at that time.

[Di3s3l_Power]

^ is drop and refill not flushing

from my understanding the flushing can be bad as it can clog channels if there are any impurities in the oil (especially higher mileage)

I think the key is to ask for drop and refill service and not flushing

[eelnoraa]

Originally Posted by Blueboxer

My mechanic offered to change it right before the warranty was up, he said in his experience it will fail soon after the change or not at all so if you don’t mind paying for the expensive transmission oil, go for it. 👍🏼

Transmission fluid should not be that expansive. And at warranty mileage, if gear box fails after a fluid change, it is because 1) the job isn’t done correctly. OR 2) the transmission has issue to begin with.

I would say 50k miles is a good time to change. Don’t flush.

[AGONXF30]

Originally Posted by Blueboxer

I would call your service department, if I recall correctly, the ZHP 8 speed is a closed system and they don't recommend doing the fluid change at all. I few people will do it right before their warranty up, figuring if it goes, it will go then while it is under warranty, but whenever I asked for a transmission flush, I was always told it wasn't recommended.

False! The ZF8HP must be service between 49K and 62K miles on average based on driving conditions according to ZF. While the fluid in the ZF is pretty amazing, if your transmission sees above 210 degrees F constantly, I would say service it closer to 30 to 40K miles. The average temperature for these boxes is 185 degree F and 200 degrees F when pushed hard, but it can reach 210 under some hard conditions.

[Di3s3l_Power]

Originally Posted by AGONXF30

False! The ZF8HP must be service between 49K and 62K miles on average based on driving conditions according to ZF. While the fluid in the ZF is pretty amazing, if your transmission sees above 210 degrees F constantly, I would say service it closer to 30 to 40K miles. The average temperature for these boxes is 185 degree F and 200 degrees F when pushed hard, but it can reach 210 under some hard conditions.

Is there a way to see the transmission fluid temperature?

[AGONXF30]

Originally Posted by Di3s3l_Power

Is there a way to see the transmission fluid temperature?

Yes, you need an OBD reader and monitor system.

[BobsM3Coupe]

Originally Posted by AGONXF30

Yes, you need an OBD reader and monitor system.

I believe it's available in the service menu in the instrument cluster. But it's a bit tricky to enter the menu.

[AGONXF30]

Originally Posted by Blueboxer

I would call your service department, if I recall correctly, the ZHP 8 speed is a closed system and they don't recommend doing the fluid change at all. I few people will do it right before their warranty up, figuring if it goes, it will go then while it is under warranty, but whenever I asked for a transmission flush, I was always told it wasn't recommended.

ZF recently changed their fluid and recently change their intervals, based on how its driven and how the load (force put on the transmission due to engine torque) the fluid must, at a minimum be changed by 93K miles or sooner based on those loads.

I think your issues is the word flush. You do not flush transmission, you drain and refill. And while some fluid will remain in the torque converter, you are adding sufficient new fluid to add renew protection. This is why you do it sooner when you are heavily using the car and adding high heat to the transmission fluid. Heat is the number one killer of transmission due to fluid deteriorating, taking away its ability to cool and maintain good viscosity in the box.

ZF used to recommend an interval of 49K miles to 62K miles (Coversions from KM). So the fluid is NOT a forever fluid and the transmission is NOT sealed. There is even a published procedure for this and BMW has done all of ZF my fluid changes. My ZF in the F30 has been drained and refilled at every 60K, I am due for a third fluid change here soon since I am approaching 180K miles.

[AGONXF30]

Originally Posted by Blueboxer

My mechanic offered to change it right before the warranty was up, he said in his experience it will fail soon after the change or not at all so if you don’t mind paying for the expensive transmission oil, go for it. 👍🏼

Your mechanic is full of a brown substance called excrement. These do NOT fail after a fluid change, particularly if they change is made within reasonable intervals posted by ZF.