Should I change the ATF fluid?
 

Hello all,

my 2005 XC90 with the Aisin AW55-50 5-speed ATF has covered about 396000 KM (248.000 miles) and I recently checked the ATF fluid dipstick...

The fluid was black and it smelled like ass and Im sure the oil hasnt been changed in a long time, maybe 300.000 km. Should I maybe change it? I have read stories on other forums on how doing a flush would cause the transmission to fail, so im a bit worried...



Maybe do a "soft" flush? Meaning opening the drain plug, put some new oil in, and then after a while do the same procedure again?

cheers, Adrian

If it were my car I'd change it.

The 'drain & fill' method is popular & many opt for that option, as the gibbons method requires removing the line to the transmission oil cooler etc. The gibbons method does do a complete flush, but its a trickier job.

With that mileage & the description you gave of the smell & colour of the transmission fluid, definitely consider changing it as soon as.

I probably wanna ask my mechanic how much he will charge for it, but I just read some places that people have had no problem with their gearboxes and when changing their fluid after they havent done it in a long time, their trans fail hard... But i dont know what to do

That's nothing more than coincidence. None of the people who claim this have yet produced any science to back up the claim. No one ever blames their last service and oil change (assuming it was done correctly) and when the head gasket fails or a conrod let's go, and its no different with boxes.

How is your car changing?

If smooth, then seriously consider leaving alone.

I was quoted £250 from Clarkes indy, that was for 2x flush with a software check and update if needed...

Change it.... if it was the engine oil, you wouldn't think twice...

There are some concerns when changing very old fluid that doing so can dislodge debris, but no-one has ever posted on here where that has happened to them.

You can mitigate the risk of this by "sump dumping" - i.e. remove the drain plug and around 3 litres will come out, do that, refill with new, drive the car a few hundred miles and then repeat. Doing that 4 times will get you around a 94% fluid change. You will notice the difference and your gearbox will be very grateful.

Interestingly (or not) I've been speaking to the Volvo dealer who has been servicing the XC70 I've just bought to understand what work it's had done.

We got to talking about ATF changes and the service agent was unequivocal. Unless it is otherwise indicated by heavy use (taxi/towing, or in the case of my 2012 it asks you via a message) think carefully before changing the fluid. He cited occasions where a customer had insisted on a fluid change and wrecked their transmission.

Thats interesting, because the fluid in mine was changed recently because a Volvo dealer did recommend it.

Either way, neither your dealer or mine presented any scientific or technical evidence to support their stance.

I know of transmissions that went South that had never had a fluid change, so there is no correlation. As I mentioned above, if your head gasket went or your engine threw a rod you wouldn't blame the most recent oil change (assuming it was done properly), so for what reason would you do the same when a transmission fails? When someone shows me some observed science behind it then I'll listen - until then all I hear is unsubstantisted opinion.