Rear Diff and Transfer Case Fluid Change: Tools, Parts and Links

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16.5 CX-5 Tour/AWD
I would ask what the viscosity will tell you or what path of research you are headed down?

Andnope, no one on the internet's most busy oil forum have not chimed in.

And I would caution of relying on viscosity as a measure of compatible oil.

seriously just buy the required SG1 - there are SO many threads to find a less expensive alternative.. but the magic blend simply is not replaceable by an alternative currently.

I'm just curious since there is no indication of what grade of fluid it is and previously, the dealer used 0000-77-80W9-QT (SAE 80W-90 R DIFF OIL) in my vehicle. So for curiosity sake, is SG1 a higher grade or a lower grade fluid and why isn't Mazda listing it on the bottle? Must be some secret sauce if they aren't willing to tell people.

I don't have any plans on using other 3rd party alternatives since there's no need but my rear diff/transfer case maintenance seems to be coming up soon. I had it changed by the dealer at 42k miles and now I'm at 64.5k so I guess at around 72k is when I should service it as I do repeated trips of <10 miles.

Also, since this guy posted his analysis for 80W-90, I'm planning to also send in mine as well for a comparison. In addition, I'm planning to send a sample of SG1 as I do not see any results on BITOG or on this forum so far.

2014 CX-5 Transfer Case & Differential fluid change and analysis
 
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2019 CX-5 GTR
... So for curiosity sake, is SG1 a higher grade or a lower grade fluid and why isn't Mazda listing it on the bottle? ...

ahh TIL

I would say SG1 is ~80W .. but also has some other ingredients to help the hypoid gears operated better.
 
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2019 CX-5 Touring
Just to add another data point, I drained and filled my transfer case and rear diff fluid on my 2019 CX-5 at 30,000 miles.

The transfer case fluid was in awful condition - it smelled terrible and was chock full of metal. Opaque with metal particles. I would've changed it after the first few thousand miles had I known how much metal was in it.

The rear diff looked and smelled good, though the magnetic drain plug was completely full. I think it could've gone much longer.

I do a fair amount of offroading so I'm guessing my fluid was in much worse condition than average.
 
I'm just curious since there is no indication of what grade of fluid it is and previously, the dealer used 0000-77-80W9-QT (SAE 80W-90 R DIFF OIL) in my vehicle. So for curiosity sake, is SG1 a higher grade or a lower grade fluid and why isn't Mazda listing it on the bottle? Must be some secret sauce if they aren't willing to tell people.

I don't have any plans on using other 3rd party alternatives since there's no need but my rear diff/transfer case maintenance seems to be coming up soon. I had it changed by the dealer at 42k miles and now I'm at 64.5k so I guess at around 72k is when I should service it as I do repeated trips of <10 miles.

Also, since this guy posted his analysis for 80W-90, I'm planning to also send in mine as well for a comparison. In addition, I'm planning to send a sample of SG1 as I do not see any results on BITOG or on this forum so far.

2014 CX-5 Transfer Case & Differential fluid change and analysis
Did you end up sending off your oils for analysis?

Blackstone?
 

Kedis82ZE8

'12 GX 460,'07 G35x / '15 CX-5 AWD GT w/Tech Pkg
Contributor
I'm changing the front transfer and rear diff on 25-30k mile intervals... easy to do and pretty cheap on the material cost side.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
I'm changing the front transfer and rear diff on 25-30k mile intervals... easy to do and pretty cheap on the material cost side.
That’s because you have a 2015 CX-5 and you use normal 80W-90 GL-5 gear lubricant. But my 2016 CX-5 needs Mazda Long Life Hypoid Gear Oil SG1 which is very expensive. Used to be $20+ now Amazon sells $32.49 per quart! And we need 2 bottles to change both front and rear!

The inflation nowadays is terrible!
 
That’s because you have a 2015 CX-5 and you use normal 80W-90 GL-5 gear lubricant. But my 2016 CX-5 needs Mazda Long Life Hypoid Gear Oil SG1 which is very expensive. Used to be $20+ now Amazon sells $32.49 per quart! And we need 2 bottles to change both front and rear!

The inflation nowadays is terrible!
I have a 2015 and I opted to use SG1. Just the same, you can opt to use GL-5 or, probably a better option, Amsoil or Redline.

$60 every 30k is relatively cheap for an AWD maintenance item.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
I have a 2015 and I opted to use SG1. Just the same, you can opt to use GL-5 or, probably a better option, Amsoil or Redline.

$60 every 30k is relatively cheap for an AWD maintenance item.
i won’t use GL-5 if Mazda switched the gear oil from GL-5 to SG1 on the same hardware.

On the other hand, I’d switch from GL-5 to SG1 like you did if I had a 2015 CX-5 or prior. There’s a reason why Mazda made a switch.
 
i won’t use GL-5 if Mazda switched the gear oil from GL-5 to SG1 on the same hardware.

On the other hand, I’d switch from GL-5 to SG1 like you did if I had a 2015 CX-5 or prior. There’s a reason why Mazda made a switch.
I agree with your sentiment, therefore one could argue that a 3x increase in fluid costs is worth the investment for future protective qualities.
 

Kedis82ZE8

'12 GX 460,'07 G35x / '15 CX-5 AWD GT w/Tech Pkg
Contributor
I feel confident in fluid I am using.

These potential rear diff design flaws below are what I am more concerned with failing





 
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yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I feel confident in fluid I am using.

These potential rear diff design flaws below are what I am more concerned with failing





Yes, I’m also worried about these inferior companion flange oil seal、“insufficient durability” of differential mount bushing、and water damage to internal wiring harness since I plan to keep my CX-5 as long as I can. Thanks for reminding me ⋯. 🙁
 

Kedis82ZE8

'12 GX 460,'07 G35x / '15 CX-5 AWD GT w/Tech Pkg
Contributor
I've ordered the replacement diff breather/vent hose mentioned in TSB to address that potential problem


KE02-27-090

Wonder if that is what caused Unobtanium's rear diff failure years ago?


Screen Shot 2021-12-05 at 1.47.05 PM.png



Screen Shot 2021-12-05 at 1.48.56 PM.png
Screen Shot 2021-12-05 at 1.49.15 PM.png
Screen Shot 2021-12-05 at 1.49.28 PM.png
 

Kedis82ZE8

'12 GX 460,'07 G35x / '15 CX-5 AWD GT w/Tech Pkg
Contributor
I'm am concerned about failure but these vehicles have been out long enough used replacements are readily available now. The big question for me is cross year compatibility for replacement.

As I typed this I was thinking about Chris_Top_Her replacing his

 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
I've ordered the replacement diff breather/vent hose mentioned in TSB to address that potential problem


KE02-27-090
Thanks to remind me and I also need to order this differential breather / vent hose mentioned in TSB. Please update us if the actual replacement doesn’t require dropping the rear differential!


Wonder if that is what caused Unobtanium's rear diff failure years ago?


Unobtanium’s failed rear differential at least helped Mazda to find out this differential breather / vent hose was having design flaws letting the water in to the rear differential, as the TSB came out 9 months after his differential failure.

Unfortunately he may never know his contribution to Mazda for fixing this issue ⋯ ;)
 
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Kedis82ZE8

'12 GX 460,'07 G35x / '15 CX-5 AWD GT w/Tech Pkg
Contributor
Will do… part should be here in a week or so and will see what it takes to install.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I'm am concerned about failure but these vehicles have been out long enough used replacements are readily available now. The big question for me is cross year compatibility for replacement.

As I typed this I was thinking about Chris_Top_Her replacing his

Belt tensioner failure on CX-5 is a known issue. Mine started leaking at 41,150 miles but haven’t got replaced yet.
 
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18 Mazda CX5 AW
Belt tensioner failure on CX-5 is a known issue. Mine started leaking at 41,150 miles but haven’t got replaced yet.
The more read, the more find that it seems the Mazdas have leaks or breaks.

Aside from normal maintenance, oil/fluid changes, brake pads, & alternator replacements my last 2 vehicles ( Ford and Toyota) had no issues up to 200k miles. The only issue with the Ford was hard to reach alternator and difficult to change the back 3 sparks without either removing almost every single part near/around the engine or lifting the whole engine. Those were more like inconveniences.

But it seems here with the Mazda, gotta worry about possible NA engine having issues( seems the turbo definitely has issues), leaking shocks/struts, leaking differentials, rear liftgate strut failure, etc.
It seems like there is a TSB for everything.

Will have to catch up on all the TSB before the cpo 12k bumper to bumper expires in another 5000 miles( probably February)

We'll see what happens.

Was considering moving up to a CX50 in future but if multiple problems will get a Ford Maverick next time.
 
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Kedis82ZE8

'12 GX 460,'07 G35x / '15 CX-5 AWD GT w/Tech Pkg
Contributor
Belt tensioner failure on CX-5 is a known issue. Mine started leaking at 41,150 miles but haven’t got replaced yet.

I keep a close eye on the tensioner. Not leaking yet. I am just about to turn 66k miles so spark plugs likely next summer.