Original Transmission Fluid at 117K Miles - Drain, Flush, or Leave Alone?

CX-9 Owner MD

Member
:
2008 Mazda CX-9
I own a 2008 CX-9 with 117K miles which still has original transmission fluid, yup, never replaced. After this realization, I have spoken both with a local mechanic I trust (although admittedly not a Mazda expert), as well as the local Mazda Dealer (who I only partially trust). Although the manual does not specify when the transmission fluid was due to be changed, the Dealer tells me it should have been done (flushed and replaced) at 60K. They serviced the vehicle at 40K and 80K, but since not at ~60K, they did not pick up on the fact the transmisison fluid was never replaced. Ultimatley it's my fault (and my wife, it's her vehicle) for not paying attention to this critical fluid. The fluid is not black, nor burnt, but a little dirty. Dealer says that since over 100K, not to replace it - too risky. That gears might not line up afterwards. Mechanic says if a drain and fill, not a flush, makes sense to replace it now. Asst Service Manager at Dealer says they don't do a drain and fill, only a flush, since it holds 12 quarts, and a drain and fill only replaces ~5 quarts, so 7 quarts would still be original/dirty.

Thoughts on what I should do?
 
I am not sure but I think I had my transmission fluid changed on my 2008 GT around 50K. Then forgot about it. Over the years I remember getting my trans oil changed at higher mileage and having the trans screw up ( rough shifting). So, I debated about it and got some of the same stories you got about drain and fill vs flush but never changed the trans fluid again. Never experience a shifting problem at 160K. A couple of months ago I decided to make an 1800mile trip and figured I didn't want to risk it. So, I bought a 2015 to make the trip.
 
Some people on the forum have done 3 drain and fills over a few days to get the fluid as red as possible. Maybe you can do that. I would search the forums to see what others have done. I have always taken it to the dealer. The first time at 36k and they told me every 30 thousand miles after. The second one I did after 30 thousand more miles and the 3rd after 25 thousand miles. The next one I am taking it in at around 99k which would be 20k miles since the last flush. I will probably being doing it every 15 to 20k miles. It is very cheap insurance since they only charge 150 for the service with the coupon.
 
Drained mine at 100K km. ...... after the transfer case went (lucky it did not strip the transmission splines).

I did an initial drain and fill (3L)(not good at all), drove it around the block and repeated (still ugly). I then went for a week or so and did another repeat (now looking sort of half bad). Further on 6 months or so - did it again when changed the engine oil + filter (It is now starting to look more like the red it should be). I imagine I will monitor it and most probably give a drain + refill each 12 months. I have a place near me where I just buy Mobil 3309 by the case.

I have found getting the fluid level just right a little fiddly - level right when at correct temperature is a fine line between low and high on my car.

By comparison, when I changed the rear diff at 100K km, the colour of the fluid looked perfect (level of shear unknown as I did not test anything - just started to change everything!).
 
Which store did you buy the mobil 3309 and how does the trans act with that particular brand of trans fluid?
 
I am in a different country - but I have a great guy who imports all the goodies from the US - the Mobil 3309 is one of them.

Transmission acts like it is supposed to. The manual specifies a JWS3309 oil for the transmission - hence I used Mobil 3309

By the way - it could be (I am not certain) that the Toyota IV is the same stuff. http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2995984

There are some other threads in the forum on how to change the transmission oil.

Cheers
 
I would just drain and fill each time you change your oil until the fluid looks nice and red. Then do it every other time, since you are up over 100K. I'm assuming you'll have your mechanic do it, so the cost is negligible compared to the preventative value.
 
Back