I've got an '05 ML 350 with about 67,000 miles on it. In my understanding the transmission has never been serviced thus far. I'm wondering, at what mileage does the tranny fluid/filter need to be changed. Or is it one of those "lifetime" transmission fluids?? Any info would be greatly appreciated.

 

Yes, "lifetime" they thought, untill the MB engineers waked up and their coffee was cold!
It is not a lifetime, non of the fluids in your cars is a lifetime fill, I believe. And now, even MB knows it. You can call them and ask about it. Have it checked for correct level and discoloration, you should be fine till 100,000 miles. I will check my ML Star manual for replacement intervals. I'm happy, I bought my ML320 with broken transmission because guy believed it was "lifetime" that expired for him at 132,000 miles. Better terminology would be "warrantytime" for it, but that is just my opinion! Bernard

 

I think it's very similar to engine oils. Mercedes is using full synthetic fluids and as oil changes will last 3 time longer, same as the ATF fluids should last. Even doe I can never wait 10k miles for my oil change, I would suggest changing the ATF fluid at 60,000 first time and 90,000 miles every other ones.