Changing CX-9 transfer case gear oil (photos)


2014 Mazda CX-9
I have found my way to this thread due to the burnt oil smell in the passenger cabin issue we are having with our 2014 CX-9 AWD (58900 miles). I crawled under the car and reached up on top of the PTU and found the sludge and the smell. There was a lot of what I can best describe as grease on top of the PTU. I cleaned it all off with a ton of rags and made sure the vent was clear, then I cracked open the fill port on the PTU and no fluid came out. I really was not expecting any. However not having an electric pump I am finding I am not pulling very mush fluid out, much less than those using the electric pump method. I am wondering, Is this an assembly where I could spray in some type of detergent to break down the sludge and then suck it out?. The best I can hope for now is to fill it with the Mobile 75W-140 I purchased and drive it around for a couple hundred miles while I wait for the electric pump to show up via Amazon. If anyone has used a mild detergent before to break down the sludge inside let me know. Also has anyone replaced the PTU unit before and can give an idea of time required to replace working off jack stands.
2010 CX-9 GT AWD
Sorry for digging up an old post.
I really want to know who has highest milage after you replace transfer case oil?
My 2010 with over 106K now but has no sign of burn smell or other engine related problems.
Did I get lucky with my car?
2010 CX-9 GT AWD
I did it today.
I do have floor jack and stands but I went to drove my CX-9 on 4 pieces of 3.5in blocks to make me feeling safer.
Locate and remove transfer case plug was easy and my 8in socket wrench did a good job.
Once plug removed, I can see oil deposition on it as shown in OP picture. I also notice the back of plug is a magnet (to catch metal particles).
I was trying to suck old oil out but nothing. I then decided to pump new in. Let it sit for a while, then pump it out again. Yes, it came out and all black.
I only did twice. 3 pumps in and 2 sucks out. Planing to do more later. I tested transfer case by lift up the car, I release the break slowly and watch for rear wheels to spin. It works, no noise.
Technically, the transfer case has not died on me just yet probably we barely use it. We have less snow in NW WA, we don't tow and no up/down hill driving.
That's why our CX-9's transfer case still survived.
I am planing to change rear differential next day since I don't have right size socket now and getting tired already.
BTW, I used Volvaline oils for transfer case and read differential.
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I have a datapoint for this. Just completed this project today. 2014 CX-9 with 61,000 miles. Yes, I know, long overdue. However, the fluid that came out was OK. It was darker but not black and flowed freely. The plug, as you can see was quite caked up.

There was no evidence of any overflow from the case, no burned smell, and no issues. I noticed that the cat had a heat-shield and maybe that helped prevent from the fluid to be cooked off?

I live in Indiana (no hill driving). My wife was driving this car mostly, city driving and no towing.

Anyway, we plan to keep the car for a while so I think this is a cheap and worthwhile maintenance item.




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2013 CX-9 AWD, 2016.5 CX-5 AWD
for 1st gen (2007 thru 2015) CX-9 AWD CX-9 AWD only,

hope this info is useful for some fellow Mazda owners.

the Ford PTU in these videos is the same as in the 1st gen CX-9 AWD


I need help and suggestions if possibly I can drive Cx9 without PTU just as front wheel drive. Actually I purchased few months back and immediately then replaced PTU fluid due to some noise. It was quite for few months after fluid change but now noise came back again. Mechanic replaced the fluid again but sound is there so advice me to replace with new unit. Car is not worth to spend $$$$ and here in U.A.E temperatures are extreme and winter is also mild no rain also, so I will be fine with front wheel drive.

Please share any link if someone successfully done it as front wheel I tried to search on forum but no success.
You didn't search hard enough, it has been discussed many times in this forum, do a search under my name I explained it a couple of times. Short answer is yes it can be done.


You didn't search hard enough, it has been discussed many times in this forum, do a search under my name I explained it a couple of times. Short answer is yes it can be done.
Not everyone is familiar with how best to use the search function etc...Kindly pointing them in the right direction would be a better way to respond.

@coolbema I believe puma is referring to these threads...
Mazda CX-9 Grand Touring 2016
I saw a question above about a cleaning product. Auto-RX is one I've used for engines and automatic transmission with very good results. I'd follow the instructions for differential cleaning if I wanted to clean the PTU. and, of course, if the parts are already damaged then no chemical can repair them.

The video shows ways to drill a drain hole. One trick--coat the drill bit with heavy grease to catch chips and keep them from going inside the case. If the case was iron or steel the bit can be magnetized to hold the chips, but these cases are aluminum.
Thanks Antoine for understanding!

As suggested by Puma, I clicked his id and landed in several posts and threads. I have gone through many posts but unfortunately didn't find any video how to make it 2wd.
There is no video as far as I know. You remove the transfer case and the driveshaft to the rear and that's it. I don't know if the passenger side front axle has to come out and go back in during the process.
Thanks guys for help.

I checked with my local mazda dealer they refused to remove the PTU and making it 2wd. Basically they said PTU also work as support for right side axle shaft if they remove PTU they no longer can connect the right side axle to transmission its short in length and it has some extension from PTU to transmission.

Well I'm not a mechanic so what I understood if I remove PTU I have to use some connection to extend the axle to transmission.. Please correct me if I'm wrong.
The support for the right axle is on the engine block, not the PTU itself, they are wrong. Also, the right shaft goes through the PTU. They can't see it from underneath if they never did a job like this, you can remove the right drive axle without taking out the PTU. There are 2WD CX9 and they basically work the same way.

Please go somewhere else than a dealership for that kind of job, of course they won't do what they consider a hack job on a client's car, get a good indy shop to do the work for cheaper, it is very not a complicated job for any average mechanic.
here's a quick write up on how I changed the CX-9 (AWD models only) transfer case 75W140 gear oil,

Step 1.

need to get some front ground clearance to get under the SUV, so I got some 4" thick solid cement blocks (they run about $1.44 each per block) from Home Depot or Lowe's and rolled both the front wheels up using the 2" high red bricks as a helper to get the wheels up the 4" thick blocks. I then chocked the rear tires just as a safety precaution in case the truck rolls back (highly unlikely but can never be too safe).

*note: you must use the 2" red bricks to help get up the 4" cement blocks otherwise the truck gets stuck and just pushes the cement blocks. You may also do the same setup for the rears to be absolutely level front and back but I felt it was unnecessary since it was just a slight 4" rise up front.

I find it easier and safer to just roll up the blocks then jack up the car on one side.
also it keeps the car level on both sides at the same time and the 4 inch rise provides just enough clearance to get under the CX-9 without too much incline, since we need to fill the transfer case and it needs to be as level as possible w/o too much incline.

SAVING $1.83 is not worth your sight !!

Step 2.

need to locate the transfer case fill plug (it's the one with a 3/8" square drive cavity and orange thread sealing compound)

a led light with a magnetic base will help, it's very dark down there

the transfer case is located underneath approximately between the driver and passenger seats, it is near the engine oil drain plug,

follow the U pipe you see in the photos below and you'll be able to see it ,
you'll need a short stubby ratcheting 3/8" socket driver (make sure it is the low profile type);
the head of the 3/8" drive can just barely fit ! there is a metal plate on the opposite side of the 3/8" drive
we got lucky, if any more tighter, we wouldn't be able to get the plug out due to the stack up tolerance
of the loosened plug + ratchet head. (commissions earned)

there's a stupid black cross beam right under the plug, so I had to access the plug from the left side of the beam and cross over to get to the plug with my stubby ratchet, it is hard to explain, you'll understand when you see for yourself.

here are some pictures of the transfer case plug removed, note the black gear oil and sludge,

see here for Ford Edge/Flex AWD problems (they use the same exact transfer case as the CX-9):

my CX-9 AWD only has 38,000 miles mostly highway miles (I cannot believe Mazda calls this lifetime oil) Based on some investigation from the Ford Edge forum, the Ford Edge uses the same exact transfer case and the OEM oil is Motorcraft brand 75W140 gear oil and new oil color is suppose to be an amber yellow color which indicates to me my oil is beginning to break down since it's dark and black.

Step 3.

need to suction out as much as the old oil as possible

you'll need a suction gun, the gun comes with a short 1/2" OD PVC tube. I found this to be too short and too rigid to get it thru the transfer case hole, so I bought a longer more flexible 3/8" OD PVC tube, I had a heck of a time getting that smaller 3/8" tube on the suction gun barb connector but trust me it will fit just need to force it on, the longer tube definitely helps when you're under the car and the smaller OD allowed me to snake the tube deeper into the transfer case hole.

I experienced the same thing as some fellow members reported, it seems the tube hits an obstacle and cannot get all the way into the transfer case, you'll probably get in maybe an inch and a half before you can't go any further, I then started to suction the old oil, got about maybe 1/2 of a cup before the suction gun was just sucking nothing but air. (commissions earned)

this is a picture of the 3/8" OD PVC suction tube in the transfer case sucking out the old gear oil

here's a video of the old oil in the suction gun , notice how thick and black the transfer case oil is only after 38,000 miles, the smell is absolutely acrid :

****************************************************************************************************************************************************************************************************************May 2, 2015 update***

I switched to an electric sunction pump which makes the job a lot easier and cleaner,
see link:


Step 4.

after you suction out as much of the old oil as possible, you need to refill with new 75W140 gear oil,

this is straight out of the CX-9 owner's manual, I cannot believe the gear oil capacity is only 1/2 a quart,
that's way too little for this size SUV and transfer case, no wonder we're having so many transfer case issues and burning oil smell, the gear oil is breaking down over time until it no longer lubricates the transfer case gears and the transfer case literally burns itself out

you need to buy a pump with a 3/8" PVC tube to get the new oil into the transfer case (commissions earned) (commissions earned)

Step 5.

keep pumping the new oil into the hole and try to flush out as much of the old oil as possible, once the oil that is coming out of the hole becomes clear or lighter , you can stop pumping and wait for the oil to stop dripping,

Wipe clean the plug threads and thoroughly wipe clean any excess oil that dripped down on to other components (otherwise the smell will permeate into the passenger cabin).

Reinstall the plug and you're done.

You can use a torque wrench if you want, it'll have to be stubby wrench though, the space is very tight, sorry I don't know the exact inch-lb torque specified, I just made sure it was tight, you don't want to over torque it though, the transfer case is casted metal and will crack if you over do it, so be careful.

Also, you can add more orange thread sealing compound, just a little if the original got stripped.
I didn't need to since my original OEM orange seal stayed on and it's suppose to be reusable guaranteed
to 5 times.

But just in case, this is what you need in case yours get stripped, it's made in the USA by ND Industries
Vibra-TITE VC-3 Threadmate. It's much better than Loctite or white liquid teflon for vibration and sealing. You spread it into the threads and let it dry and it dries to a rubbery coating that seals and keeps the plug from coming loose. And oil on the mating threads does not inhibit performance. (commissions earned)

Final thoughts...

I have driven 1500 miles since this transfer case change and happy to report everything is smooth as silk, it definitely seems the vehicle drives smoother during the gear shifts and no burnt oil smell.

Since the process is so easy, I decided to do the procedure again and take a look at the oil condition this weekend, below are a picture of the plug and oil after 1500 miles. The oil is definitely less viscous than before, it flows way smoother. The color is still black, probably from the leftover black oil that the suction gun couldn't reach but I'm sure after two more changes the black color will be eliminated.

I recommend doing this maintenance every 20,000 miles or less, I myself is leaning towards the latter maybe even every 6000 miles when I change the engine oil might as well change the transfer case oil as well.

The oil capacity in the transfer case is just not enough for it's size. Because of the low capacity, the oil breaks down quickly causing the burnt oil smell and eventually transfer case failure.

From a technical view, I submit it's not how hard the car is driven but rather there are two factors to consider when dealing with this low capacity,

1) length of continuous driving

this is just my theory, but if the oil has indeed broken down and driving the car for more than say 3 hours continuously, I believe there will be overheating issues

2) cold weather, when it's cold, the oil is pretty thick and can't lubricate the gears enough

Maybe some owners who had their transfer case replaced can chime in and help us out, is your daily commute a long drive and do you live in a cold part of the country ? and at what mileage did you encounter transfer case issues ?

Personally, I would consider changing the oil before a long road trip with the family just to make sure the transfer case doesn't overheat AND changing the oil right before the cold winter season every year.

A good analogy would be like never changing the engine oil, who would ever try to run an engine 100,000 miles without changing the oil:

Same thing here, gears in the transfer case are running all the time and Mazda expects the oil to last 100,000 miles, I think not.

*note: some dealerships who are willing to do this transfer case oil change service will charge ~$159
most dealerships won't even try and will say it's a sealed unit and cannot be done, blah, blah, blah .....yeah right

Finally, I suggest a transmission fluid change every 30,000 miles
and rear differential fluid change every 30,000 miles.

I'm pretty sure I can get at least 150,000 trouble free miles with this maintenance plan, *knock on wood*
2012 Mazda CX9 Grand Touring AWD.

Thank you for the great write up! Will be very useful for myself. I actually had to replace my transfer case, well a local mechanic did. I was driving to work one day and heard a loud thud and my rear wheel bearing was going out, i thought it finally locked up.

Tow truck came and drove my car on the back. I pulled in my garage replaced the wheel bearing went around the block and heard another loud thud. Looked under my car and my transfer case was blown apart literally. I could see the inside gears. I limped it down the road to my mechanic. He said it would be much cheaper to buy the OEM brand new transfer case as it had been re designed rather than buying a used one with 50k miles on it. He replaced it with parts and labor for 1200 bucks. When he took it out he said all the oil in it was clumped up. he said its because it sits right above the exhaust and just gets super hot and cooks itself.

He said he would replace the fluid for me every 30k miles but i may attempt the change myself now that i found this post. Thank you so much!


Zoom Zoomin'
2011 CX-9 GT
Yes one quart is actually more than you need, hopefully you'll get a lot of the old gunk out. It amazes me to this day how little fluid is in there.
Thanks! I ended up getting Pennzoil Full Synthetic Gear Oil 75W140. Not sure about the RP stuff as I've seen good and bad about it. I know OP has had success with it over the years, but I'm not convinced. I like Pennzoil's full synthetic motor oil better than other motor oils I've tried over the years so have some level of confidence in the brand. Going to try to replace the fluid some time in the next few days.

My original transfer case was actually replaced at ~50k kms. It had started leaking and I could smell a nasty sulfuric odour. Eventually it started making noise so I had it replaced on warranty. I'm now at ~150k kms and haven't noticed any issues, except for a little bit of sluggishness changing gears, which I thought was transmission related but is still there even after I replaced the transmission fluid, so I suspect it might be related to the transfer case.
Hi @avidien (and others), very excited to find this thread as I also own a 2013 CX-9. I have a few questions, hopefully someone can help me:

1. What are the specs for the front differential oil? Didn't say in the manual.

2. How much brake fluid do I need? I have a 1 Qt DOT3 from Wearever, will this work?

3. Is the "automatic transaxle fluid" the same as "transmission fluid"?

Thank you very much!