Old thread - Transmission fluid

[is200 Newbie]

Its an old topic - one that created a lot of debate over if it could be done or not - either DIY or by a dealer

Question remains ... can the transmission fluid be changed

IS owners in Canada / New Zealand and US have had fluid changes and are done on a regular basis - some state its on their service schedules yet owners over here state it cant be done and its on no schedule I have seen. So is this climate dependant? You can argue as its a sealed unit (lifetime oil) then whats the difference in running a car in a different climate as its cooled the same?

I am not an expert on oil but have to question whether a lifetime oil means lifetime - what determines the lifetime of a car? 100k,200k,500k? Surely an oil under pressure as the fluid is in an auto box is and under constant heating and cooling will after a while break down along with the moving parts within the box - if it doesn't then its a miracle oil as metal on metal will wear and deposit debris in the oil creating more wear and tear - to be honest I am quite surprised after doing a bit of research on this that its not a part of a regular service item. Why is there a filter in there if its not designed to be maintained? Surely as per all filters it will act as a filter for the oil and need maintenance?

There is a drain hole and a fill hole on the box - surely that's there to offer maintenance to the box. If it was not meant to be maintained then there would only be a fill hole?

I believe the oil used is very thin - it is cooled through the cooling system of the engine - explains why the cabin can heat up quickly if using the car in manual mode as its putting pressure on the box more than the control the auto feature has over it. The process in most of the topics I have read have all indicated that the oil change is done in stages by replacing a percentage of the oil at a time and always with the same oil originally applied to the box with a further change done a few weeks later thus ensuring the oil is gradually replaced with new and not in one go. Forums state its not recommended to flush the boxes due to the solvents involved in doing so. The reports from a few forums have stated in each case when changed after long periods the oil looked cloudy and burnt. Not ideal for what is an essential part of the car that can easily be maintained by an oil change

Its a very hard job to do without the correct tools and is best left to experienced mechanics / dealers.

Anyone had this done?

[NemesisUK]

On my 2016 RC300h the atf is to be inspected every 36months and replaced every 72months.

MB used to have 'sealed for life' transmissions but that quickly changed..

What harm can it do to replace the atf a regular intervals?

I would change the fluid and filter if it hasn't been done..