tounphic

I have an 2012 Audi A6 with 8 speed ZF transmission and 170,000 miles on it(Yes, you read this number right). Recently, I felt the the transmission did not shift very smooth(but still acceptable) at some condition(not every time), especially the first three gear.

Some friends recommend me to change the Transmission fluid and filter, but the others said that base on the miles of the car and maybe still has the factory fluid in it, changing the fluid will cause serious damage to the transmission because they have seen a lot of case like that. I also email the ZF company which manufactured this transmission, they said they recommend to change the fluid(only drain and replace the filter, Not flush) at every 60,000 miles. This reply did not answer my question directly.

I am very confused right now, here is the question: I want to keep this car as long as I can and in order to prolong the life of the transmission. Should I change the fluid now or just leave it like that?

Any information will be appreciated, Thank you

Mesquite77

What works for my other older cars, is to drain and fill the tranny 3 times (driving a few miles in between) instead of "flushing". In the old days, when trannnys wore more (due to materials used back then maybe?), a lot of sludge would build up, and "flushing" could force it into small channels plugging them so the theory goes.

The 3 times drain and fill does not use any pressure, so no plugging, and it gradually refreshes the fluid since with a drain you only get about 1/2 out per time. So, ZF says every 60-70K one drain, you are due for a 3x drain and fill (go through all the gears in between).

This will be easiest, cheapest attempt to fix the issue, and works a lot of the time. Measure how much you drain, and only replace that much, overfilling bad too.

davidglt66

changed mine at 60,000 along with the differentials, three different fluids , good insurance for the long haul, 75,000 on my 2014 TDI, runs and shifts like new, note it was drop the pan, change the filter and refill NO FLUSH

tounphic

Very useful experience, thank you.

tounphic

thank you David, I also think about to change the differential fluid

davidglt66

remember that the center dif uses different fluid then the rear dif, they are quite $$