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.
WARNING !!! DO NOT EVEN THINK ABOUT CONTINUING WITHOUT WEARING SAFETY GLASSES !!
YOU DO NOT WANT GEAR OIL IN YOUR EYES EVER.
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.
https://www.amazon.com/dp/ (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):
http://www.fordedgeforum.com/topic/10914-ptu-leak-failures/
http://www.fordflex.net/forums/viewtopic.php?f=7&t=9334
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.
https://www.amazon.com/dp/ (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:
http://www.mazdas247.com/forum/showthread.php?123848368-21-electric-sunction-extractor-transfer-pump-for-transfer-case-oil-changes
****************************************************************************************************************************************************************************************************************
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
https://www.amazon.com/dp/ (commissions earned)
https://www.amazon.com/dp/ (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.
https://www.amazon.com/dp/ (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:
http://jalopnik.com/what-happens-if-you-dont-change-the-oil-in-your-audi-fo-1692660828
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*
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.
WARNING !!! DO NOT EVEN THINK ABOUT CONTINUING WITHOUT WEARING SAFETY GLASSES !!
YOU DO NOT WANT GEAR OIL IN YOUR EYES EVER.
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.
https://www.amazon.com/dp/ (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):
http://www.fordedgeforum.com/topic/10914-ptu-leak-failures/
http://www.fordflex.net/forums/viewtopic.php?f=7&t=9334
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.
https://www.amazon.com/dp/ (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:
http://www.mazdas247.com/forum/showthread.php?123848368-21-electric-sunction-extractor-transfer-pump-for-transfer-case-oil-changes
****************************************************************************************************************************************************************************************************************
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
https://www.amazon.com/dp/ (commissions earned)
https://www.amazon.com/dp/ (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.
https://www.amazon.com/dp/ (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:
http://jalopnik.com/what-happens-if-you-dont-change-the-oil-in-your-audi-fo-1692660828
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*
Last edited:
Also makes flushing it logical as well, to try and get some of that crap out. May cost a little more in material (more good gear oil wasted), but worth it to "do it right". 
