Auto box fluid renewal

[Carabind]

My 2017 s90 D4 has covered 75k trouble free miles, and I’d like to keep it that way.
Anyone know the recommended/suggested mileage for renewal of the auto box fluid, and is it a DIY task?

[Kev0607]

Volvo don't have a set service schedule for the transmission, unless the vehicle is used as a taxi or for towing. Take that with a pinch of salt though, as all fluids need to be changed at some point regardless of what the vehicle is used for. You're right to get it done, as it'll prolong the life of the transmission. At 75k, its definitely worth doing.

Yours will have the 8 speed auto transmission (TG81 SC), which requires JWS3324 known as AW-1 fluid. Don't use anything else, it must be that spec. Its vitally important that you use the right fluid, otherwise it can ruin the transmission.

Here's a video showing what's involved. You do need a diagnostic tool to see the transmission temp though and to reset the fluid counter. Its pretty much DIY for the most part, but there's some diagnostics required which could be a problem if you haven't got it (to read the trans fluid temp to set the level and to reset the fluid counter so the TCM knows it has new fluid).

+ YouTube Video

[Carabind]

Thank you !

The physical part is fine, and no issue for me
I have a foxwell diagnostic tool , which I’ve used for resetting the service interval and rewinding the rear caliper for brake servicing. I'll check out if it has access to the TCM and report back .

What would happen if you just changed the oil but didn’t interrogate the TCM to reset the fluid counter ?

[GrahamBrown1]

Nothing noticeable will happen if you don’t reset the counter. The most important thing is setting the level at the correct temp range which ideally you want to be able to see via a suitable tool.

[Kev0607]

For the record, the fluid in the transmission must be between 50 and 60 degrees to set the level properly. Set the level whilst the car is running.

[Bonefishblues]

Or find your local specialist with one of these machines to do it for you (every c50-60K miles is the typical interval for these 'boxes for the manufacturers who specify them):

https://www.edtautomotive.com/transmission-clean/

It's what our Indy uses, and I had it done on mine at slightly higher miles than yours. Interesting article by him:
https://hortoncars.com/volvo-news/vo...and-solutions/

[Andymharrison]

Originally Posted by Kev0607

For the record, the fluid in the transmission must be between 50 and 60 degrees to set the level properly. Set the level whilst the car is running.

Purely out of interest, I understand the temperature bit as the oil has a significant expansion coefficient but does anyone know why the engine has to be running?

You want all your engine all in the sump when you pull the dipstick to check (if you are lucky enough to have one) you'd expect the same would be true with the gearbox.

[Backinavolvo]

There is a 2 piece (2 level) drain plug which is designed to drain surplus oil while running. If you don't run it, it won't get to temp.

I have done 3 services on mine, no one expect specialist dealers have the tool to read gearbox ecu to reset. I stick a temp probe in the fill port. (But airbox needs to be out to gain access.)

Software reset I ask dealer to do.

No problems so far. Make sure you have all the o rings etc ready.

[Kev0607]

Originally Posted by Andymharrison

Purely out of interest, I understand the temperature bit as the oil has a significant expansion coefficient but does anyone know why the engine has to be running?

You want all your engine all in the sump when you pull the dipstick to check (if you are lucky enough to have one) you'd expect the same would be true with the gearbox.

Transmission fluid is thin... it has a different viscosity to oil (completely different fluid). When the engine is running at at the correct temp, it allows the fluid to release from the small drain plug easy because it gets thinner with heat. If you drain the fluid when the engine is off, there's a chance too much fluid will come out because its thicker when cold. Then you risk running with a low level of fluid because you can't set the level with fluid that isn't at the right temp.

That's why this must be done with the engine running and the temp of the transmission fluid between needs to be between 50 and 60 degrees, as specified by Volvo. Diagnostics is required for that, otherwise you won't know what the temp is. I've seen people doing it with infrared thermometers, but that's not as accurate as actual diagnostics.

[Andymharrison]

Originally Posted by Backinavolvo

There is a 2 piece (2 level) drain plug which is designed to drain surplus oil while running. If you don't run it, it won't get to temp.

That depends on the gearbox, the older ones have a dipstick which is much more sensible, you can leave the airbox in place.

You obviously have to run it to get to temperature but every guide I've seen says to leave engine running while checking the level, either with the dipstick or the level plug underneath.

Just curious as to why. I've always assumed its because the torque converter needs to be moving to pump oil and get the same level in both parts but that's just a guess.