2021 CX-9 Maintenance Question

:
2021 CX-9 GT AWD
Hello all. My wife just picked up a 2021 CX-9 GT AWD. I've been looking through the owners manual to familiarize myself with the maintenance as I prefer to do all routine maintenance myself. I noticed that the manual says nothing about fluid changes for the transmission, rear diff, and transfer case. I found a page on a Mazda website that says Skyactiv transmission fluid is good for the life of the transmission. Is the same true of the rear diff and transfer case fluids?

I'm highly skeptical that these fluids will last 100k miles or more and still do their job as they should. I've changed these fluids in all vehicles I've owned before, and they were all part of the maintenance schedule for those vehicles. The 2013 Pilot this is replacing had me change rear diff fluid at 12k and 40k, and ATF and transfer case fluid at 30k and 60k.

This is our first Mazda/Skyactiv vehicle, so maybe there's something I'm missing. Thoughts anyone? Grateful for any feedback. Apologies if this has been discussed previously - I did a search and didn't see anything specifically related to my question.
 

sm1ke

Work In Progress..
Moderator
Contributor
:
Canada
:
'18 CX-9 Signature
Like you, I'm also skeptical that the fluids will not need to be changed for as long as I own the car (assuming I end up driving it into the ground).

These cars do have a transmission oil dipstick and fill plug, and the rear diff and transfer case both have fill holes and drain plugs. Luckily one of our members was kind enough to document the process for all of these procedures. Here are a couple of links - please note that these can also be found in our CX-9 Resources here (along with a lot of other potentially useful info).

Transmission fluid drain and fill
Transfer case and rear diff fluid drain and fill

If you plan to keep it, I'd change the fluids. If it's a lease or you plan to sell it before the warranty is up, I wouldn't worry about it as much.
 
:
2021 CX-9 GT AWD
Thank you @sm1ke for the helpful post. It is a purchase, and we plan on keeping it for a quite a while, so I'll likely be changing the fluids at some point.

Also, thank you @Silly Wabbit for the write-ups - very useful.

I guess the mileage for these services just comes down to my best estimate, since there is no recommended mileage in the manual? Maybe I'll plan on tackling these around when the base warranty is over.

Still really surprised to see these omitted from the manual. If the fluids are intended to last for the life of the vehicle, then the manual should say so. But don't just leave them out of the manual completely.

EDIT: Here is the page where Mazda says that the Skyactiv transmission fluid is good for the life of the transmission: http://mazda.custhelp.com/app/answe...ly-change-the-transmission-fluid-in-my-mazda?
 
Last edited:
Thank you @sm1ke for the helpful post. It is a purchase, and we plan on keeping it for a quite a while, so I'll likely be changing the fluids at some point.

Also, thank you @Silly Wabbit for the write-ups - very useful.

I guess the mileage for these services just comes down to my best estimate, since there is no recommended mileage in the manual? Maybe I'll plan on tackling these around when the base warranty is over.

Still really surprised to see these omitted from the manual. If the fluids are intended to last for the life of the vehicle, then the manual should say so. But don't just leave them out of the manual completely.

EDIT: Here is the page where Mazda says that the Skyactiv transmission fluid is good for the life of the transmission: http://mazda.custhelp.com/app/answers/detail/a_id/73/~/do-i-need-to-regularly-change-the-transmission-fluid-in-my-mazda?

I've always changed my manual transmission cars' MT fluid at 30K. Dealers always thought I was mad. The cost was cheap (1L of fluid and .2 hour of maintenance) so I never thought twice about it.

The CX9 is my first ever automatic. I think I'll have it changed every 40 or 50K miles? I'm doing less than 10K miles per year.

The CX9's torque converter feels 'locked' much of the time. I wonder how this will impact fluid life (potentially extending it?).

It's worth mentioning that BMW also claims that their ATF fluid is lifetime. Shame on them as well...
 
:
2010 CX-9 GT
Lifetime fluid is a self fulfilling prophecy - when the transmission fails due to the fluid burning up, the fluid lasted the life of the transmission. Neat.

I'd do the drain and refill thing every 40k or so. The first time you do it, compare the old fluid to the new fluid (color, smell). If it is dark or smells burned, consider doing the drain sooner next time. Or, take it somewhere that can remove all the fluid (not a power flush, just an exchange) every 60k miles or so.
 

sm1ke

Work In Progress..
Moderator
Contributor
:
Canada
:
'18 CX-9 Signature
The CX9's torque converter feels 'locked' much of the time. I wonder how this will impact fluid life (potentially extending it?).

I've seen someone else mention this as well. I'm not familiar with transmission specifics, but if this is the case, Mazda should have explained why on the page that @camaro322hp listed. It's not enough to say that it's different - they should at least give a high level explanation for why it's different (at least IMO).

That said, quite a few CX-5 and some CX-9 owners have reported that when they did change some fluids, they found that they were underfilled. So even if you decide to take Mazda's word and never change the fluid, it may be worth checking fluid levels anyway and topping up (if needed).
 
:
2021 CX-9 GT AWD
Thanks everyone for the input. I'll definitely be changing the fluids at some point. I just wish the manual gave some reasonable guidance for when. For now I'll plan on targeting every ~50k to change all these fluids.
 
I've seen someone else mention this as well. I'm not familiar with transmission specifics, but if this is the case, Mazda should have explained why on the page that @camaro322hp listed. It's not enough to say that it's different - they should at least give a high level explanation for why it's different (at least IMO).

That said, quite a few CX-5 and some CX-9 owners have reported that when they did change some fluids, they found that they were underfilled. So even if you decide to take Mazda's word and never change the fluid, it may be worth checking fluid levels anyway and topping up (if needed).

This is a nice explanation on the Mazda torque converter approach (re 'lock up' for direct feel):


Theoretically, if the torque converter is not locked up as often you're relying more on the fluids to do the work.