Hi everyone, I have a 2005 XC70 with 175K miles on it. I bought it with 110K. It runs great! I’ve heard that changing the trans oil on such an old and high mileage car can do more harm than good. I haven’t changed it yet and not sure if previous owners did. The dip stick color is not terrible, but definitely not super clean either. I drove the car about 5K miles per year and hope to keep it for about the next 7 years. Would you change the trans oil or not mess with it? Why or why not?
This is a very opinionated and controversial topic to say the least…
If you have zero history on the transmission maintenance or repairs then I would highly recommend taking it to a transmission shop and have them check it out 1st…
Changing your fluid cannot cause any damage by itself, if everything is fine inside the transmission… The issues start to appear when you change the fluid if your clutches are already worn or damaged from use. If you go and replace the fluid after they are already worn out. this can cause slipping…
Look at the color of the fluid, smell the fluid,… And worst case, drop the pan and use a transmission drain pan to catch all the fluid that comes out and then see what all is in the pan… An experienced transmission builder can tell the differences in materials in the bottom of the pan, like friction material, variety of materials, such as bronze, steel-backed babbitt, plastic, nylon, or cast iron, parts of snap-rings etc etc… You can feel the grit from the clutch friction material…
You can put the old fluid right back in it if it looks like it will require a rebuild… Done it many times when a customer didn’t want or have the budget to rebuild the transmission…
What happens is the same friction material that makes the clutch friction disc grip to the steels in the clutch packs (bands are the same way) as it wears off the friction material from the disc mixes with the ATF and causes it to grip… Remove that gritty fluid and put in fresh ATF, now you no longer have (or very little) that grit in the fluid as well as on the clutch fabrics (disc) and now it slips or no longer moves under it’s own power…
These are what old (used) good friction disc look like during a rebuild… Notice the teeth on the inner part of the disc…
These are very bad friction disc on a rebuild… to the right, notice the inner teeth disc, the friction material is about gone…
And these are wasted… lol
EDIT: Without any history, you could have a factory new transmission with low miles, but then again it could be worn out…
2 Likes
Can the new fluid pick up sediment and redeposit the sediment elsewhere? I would change it and then change it again one tank of gas later. Probably a 3rd time too.
Removing the pan if it has one and cleaning off all that sediment is a must during the first fluid change. If it has no pan then I would change the fluid like 5 times.
Doesn’t the XC70 from that year have a transmission that it well known for failing? I would get that car if it had a manual transmission.
If it came to my shop, I would drop the pan and see if any glittery material is in the pan.
If so, I would reinstall the pan, fill the transmission back up, and tell you start looking for another transmission or vehicle.
If not, I would change the filter, reinstall the pan and flush the transmission fluid.
Tester
1 Like
It is an Aisin -Warner AW55-50SN transaxle…
It basically has been used in (internals, cases may differ)
- Volvo 2001-2007
- Nissan 2004-2007 (RE5F22A)
- Saab 2002-2007 (AF33-5)
- Saturn 2003-2004
- Chevrolet Equinox 2005-2006
- Pontiac Torrent 2006-2008
The Saturn vue 3.0 and equinox 3.4 used an Asian af-33 for awhile.
I have both. Now.
They do not have a removeable pan. Ya, same guts, different cases. Uses toyo t-4a fluid. You can drain them via plug and fill them.
Does aw55 use same fluid? With same guts as af-33?
No idea about the fluid, would have to just look it up, I normally always had a fluid guide book that was used or a big chart on the wall depending on work place at the time, fluids can change from year to year, I think at one time Nissan Maxima had up to 4 different possible fluid types, so I am not trying to remember most of who takes what…
But different makes and models can call for different specs on the clutch friction as well as how many are in a given clutch pack as well as thickness, normally 3-5+, the more clutches the more torque the transmission can handle… They can also vary from planetary pinion count, some have 3-4 some HD up to 6 maybe even more… also lock up and non lock up torque coveters…
A basic A904 Mopar transmissions have 3 levels, A904 (30RH), A998 (31RH) and A999 (32RH) all fall under the TF6 line…
The A904 (and A727) for that matter have 2 clutch packs, 2 bands and 2 planetary gear sets…
The A904 has 3 disc clutch packs for both forward and direct drums, 3 pinion planets and standard 2nd gear (kick down) band…
The A998 has 4 friction disc for both direct drum and forward drum, Standard A904 bands and don’t remember what planets… lol
The A999 was the HD unit with 5 friction disc direct drum and 4 friction disc forward drum, the direct drum had to be deeper to hold the 5th clutch and steel and that gave space to have a wider 2nd gear band (kick down band), it also had 4 pinion planets for both…
Another thing that changed depending was the kick down level ratio, normally IIRC 2.8, 3.8 and maybe a few in between… I use a 4.2 ratio in mine, and of course the “Hemi” 5.0 ratio level that can cause bind up so not recommended very much…
All V8 A904/A998/A999 non lock ups used the same case and parts can be interchanged…
Also later on they change gear ratios for the planets…
I say all this cause just because they have the same basic designs they can also be changed around some as well as use different clutch friction material depending on what gear ratios, power they can hold (weight probably has something to do with it also) and what fluid they want…
Wasn’t it a lot easier when we had Type F for Ford products and Type A Suffix A for everything else?
Yes!!! lol
I always use Type F for all my Mopar 3 speed builds… 
EDIT: RWD/4X4, non lock ups (904/727)
I bought my 1999 Dodge Gran Caravan back in 2009 I believe it was. At that time it has about 200,000 miles on it.
I changed the transmission fluid immediately after I got it and have never had any issues.
I think it’s kike Dave said, if the transmission is in good shape it should not cause a problem.
After all your over heating issues you might want to change your again…
1 Like