2017~2025 CX-5 Rear Differential Failure

[stickerbush]

It’s interesting to note that the Subaru Forester couldn’t make it up the dirt incline.

Neither could the CR-V or the RAV4. The CX5 did pretty well all things considered.

 

[N7turbo]

It's also interesting that Mazda never makes much fanfare about their vehicle's capabilities.

 

[CrazyHippie]

It's also interesting that Mazda never makes much fanfare about their vehicle's capabilities.

My new 2025 CX-5 PP (non-turbo) may very well be the best value in a compact SUV on the market today. The features and design are well engineered and the price point is very good. Luxury-ish SUV for a non-luxury price. The jury is out on dependability - hopefully not too good to be true!

 

[AL Cx5]

My new 2025 CX-5 PP (non-turbo) may very well be the best value in a compact SUV on the market today. The features and design are well engineered and the price point is very good. Luxury-ish SUV for a non-luxury price. The jury is out on dependability - hopefully not too good to be true!

Like you, we will see. Our 2024 turbo has been not been back to the dealership since drove it off the lot.

This forum is priceless with info like change the differential and trans fluids. As mentioned, these two items are on our 30,000 mile preventive maintenance list.

Today, I'll check the fluid level in the rear differential. I'll continue to check the level every tire rotation.

 

[AL Cx5]

I checked the rear diff fluid level. I made a "level gauge" from a coat hanger.

Level, cold, was about 16mm below the fill port. I noted in my maintenance log the level. It's good maintenance practice to check diffs on trucks. I'll be keeping notes on the CX5 fluid level. It look clear and smelled fresh, if diff fluid ever smells fresh. LOL

I was amused to see a 24mm bolt heads to secure the fill and drain ports on this tiny, aluminum differential. It looks comical to see these oversize bolts on this tiny almost toy like, differential. Totally not needed. Mazda continues to surprise me with their OCD fasteners, wiring and wiring supports. I hope they were equally OCD with the design and metallurgy for the diff gears, axels, case and CV joints.

I WON'T be taking the CX 5 to the dragstrip or autocross tracks. I think one good launch with a turbo ECU tune, this toy diff might split in half. I've seen REAL aluminum diffs split and spill their guts on the track too many times to chance this toy.

EDIT: I found Mazda's recommend diff level. Mine is LOW! I'll be topping it off with 80W-90 Mazda diff fluid VERY soon.

I strongly suggest folks to own a 24mm box wrench and check their diff fluid or have it checked and topped off...yikes

Mazda CX-5 Service & Repair Manual - Differential Oil Replacement - Differentials

 

[BoomerZoomr]

I was amused to see a 24mm bolt heads to secure the fill and drain ports on this tiny, aluminum differential. It looks comical to see these oversize bolts on this tiny almost toy like, differential. Totally not needed. Mazda continues to surprise me with their OCD fasteners, wiring and wiring supports. I hope they were equally OCD with the design and metallurgy for the diff gears, axels, case and CV joints.

I am thinking maybe Mazda used this size fill/drain plug so a mechanic could use their finger to check the oil level and condition. Probably helps with using plastic tubing to refill as well.

 

[AL Cx5]

I am thinking maybe Mazda used this size fill/drain plug so a mechanic could use their finger to check the oil level and condition. Probably helps with using plastic tubing to refill as well.

I hope they have a reason. On my domestic 2500 pickup, I can stick my finger in the hole and check the level. But it's out in the open.

I see that the level is suppose to be at the fill hole. I've ordered Mazda fluid and a fill pump today. I'm not taking any chances the fluid is low and kills this diff.

It only holds .45l or .40 quarts. As a reference the domestic 2500 series diff holds 3 quarts! There is not much margin for error with low fluid level on this Mazda diff!

 

[sm1ke]

I checked the rear diff fluid level. I made a "level gauge" from a coat hanger.

Level, cold, was about 16mm below the fill port. I noted in my maintenance log the level. It's good maintenance practice to check diffs on trucks. I'll be keeping notes on the CX5 fluid level. It look clear and smelled fresh, if diff fluid ever smells fresh. LOL

I was amused to see a 24mm bolt heads to secure the fill and drain ports on this tiny, aluminum differential. It looks comical to see these oversize bolts on this tiny almost toy like, differential. Totally not needed. Mazda continues to surprise me with their OCD fasteners, wiring and wiring supports. I hope they were equally OCD with the design and metallurgy for the diff gears, axels, case and CV joints.

I WON'T be taking the CX 5 to the dragstrip or autocross tracks. I think one good launch with a turbo ECU tune, this toy diff might split in half. I've seen REAL aluminum diffs split and spill their guts on the track too many times to chance this toy.

EDIT: I found Mazda's recommend diff level. Mine is LOW! I'll be topping it off with 80W-90 Mazda diff fluid VERY soon.

I strongly suggest folks to own a 24mm box wrench and check their diff fluid or have it checked and topped off...yikes

Mazda CX-5 Service & Repair Manual - Differential Oil Replacement - Differentials

Just a note, for your CX-5, the recommended rear diff oil should be Mazda Hypoid Gear Oil SG1 - SAE 75W-85, API GL-4. Part number 0000-77-SG1-QT. I believe they changed the spec back in 2016. You can confirm in your owner's manual.

 

[AL Cx5]

Just a note, for your CX-5, the recommended rear diff oil should be Mazda Hypoid Gear Oil SG1 - SAE 75W-85, API GL-4. Part number 0000-77-SG1-QT. I believe they changed the spec back in 2016. You can confirm in your owner's manual.

View attachment 379126

Thanks!!

I'll check my OM in the future!!!

Reading my OM, transfer case turbo holds 0.4 quarts, NA holds 0.45 quarts. Anyone want to educate me on the difference in the two transfer cases?

AND I'm checking the fluid level in the transfer case when I get a quart of Hypoid Gear Oil SG1. All of this before we leave on a trip over Thanksgiving...

 

[nickswhip24]

Thanks!!

I'll check my OM in the future!!!

Reading my OM, transfer case turbo holds 0.4 quarts, NA holds 0.45 quarts. Anyone want to educate me on the difference in the two transfer cases?

AND I'm checking the fluid level in the transfer case when I get a quart of Hypoid Gear Oil SG1. All of this before we leave on a trip over Thanksgiving...

just fill till it starts dripping out,differences...dunno
1 quart should do both diffs

 

[AL Cx5]

just fill till it starts dripping out,differences...dunno
1 quart should do both diffs

Got it, I was wondering/hoping that Mazda beefed up the transfer case gears/axles over the NA.

We have a mild tune in the car that woke up this little turbo and about to step up to a Tier 2 tune. I hope it doesn't scare my wife when she drives it....

Neither of these gear cases inspire confidence I can really beat on this car. That's just fine, that was NEVER the intention...

 

[nickswhip24]

Got it, I was wondering/hoping that Mazda beefed up the transfer case gears/axles over the NA.

We have a mild tune in the car that woke up this little turbo and about to step up to a Tier 2 tune. I hope it doesn't scare my wife when she drives it....

Neither of these gear cases inspire confidence I can really beat on this car. That's just fine, that was NEVER the intention...

gotcha-i would ask whoever tuned it,they may know...get a few quarts and change it on the regular-it's pretty easy but pricey

 

[AL Cx5]

After finding our differential down 16mm from full after 15,000 miles, I'm checking the transfer case level today as well.

If either of these fail from low fluid, it's on the owner, not Mazda. It's like running the engine without oil.

 

[BoomerZoomr]

Now y’all gonna make me check my oil levels underneath the car
I'll have to go buy some tools
My metric stuff stops around 19-20mm

 

[Jmaz]

These low levels from the factory aren't something recent. I've been on this board for some time and remember reading about this IIRC 6-8 years ago, maybe longer. Then there's the discussion about underfill of transmission fluid, coolant (low overflow bottle level) and engine oil level on the dipstick. On a new Mazda I'd be checking every fluid level first thing.

 

[AL Cx5]

I put +-3 oz in BOTH rear diff and transfer cases today. I drained the transfer pump back into the container the best I could to see how much diff fluid I used.

That's about 30% BELOW what is recommended. Since both gearboxes were low by 30%, I wonder if this is intentional by Mazda to:
1 Increase FE
2 Save a few yen
3 The gearboxes don't need to be filled to the inspection port

We will check FE on an upcoming trip we make once a year and hand calculate FE and compare to last year.

Anyway, my gearbox fluids are filled to the inspection port. I'll check the rear diff every oil change for a while to see if it drops. It would take me half a day to get the rear differential out. So about 8 hours to swap in a new/used diff. So I'll check the level often....

I'll pull the air filter box tomorrow and check the trans level. Might as well see if it's at the correct level. I'll report back......

As a comparison, I changed the diff fluid in my 2500 Tow Pig pickup today. ONLY 285,000 miles on this rig. Just 40,000 on the diff fluid. The level was spot on after 40,000 miles. I just completed a 1300 mile trip, 650 miles towing a 9,000 pound enclosed trailer. It has a real differential that holds 3 quarts or 7.5 xs my Cx 5. It tows about 10 times the weight of a CX 5. Not that I ever expected our CX 5 to be a tow pig.

I have friends with over 400,000 miles towing on these truck diffs. The owner's manual call out changing the differential and transmission fluids. Could be Mazda is trying to reduce its's carbon footprint at the owners expense by not recommending trans and diff fluid changes......!

So much for Japanese quality being superior vs USA....

 

[N7turbo]

I'll pull the air filter box tomorrow and check the trans level. Might as well see if it's at the correct level. I'll report back......

I wanted to do that in the Miata. Turns out, it is far from being as simple as the CX-5.

 

[BoomerZoomr]

I put +-3 oz in BOTH rear diff and transfer cases today. I drained the transfer pump back into the container the best I could to see how much diff fluid I used.

That's about 30% BELOW what is recommended. Since both gearboxes were low by 30%, I wonder if this is intentional by Mazda to:
1 Increase FE
2 Save a few yen
3 The gearboxes don't need to be filled to the inspection port

We will check FE on an upcoming trip we make once a year and hand calculate FE and compare to last year.

Anyway, my gearbox fluids are filled to the inspection port. I'll check the rear diff every oil change for a while to see if it drops. It would take me half a day to get the rear differential out. So about 8 hours to swap in a new/used diff. So I'll check the level often....

I'll pull the air filter box tomorrow and check the trans level. Might as well see if it's at the correct level. I'll report back......

As a comparison, I changed the diff fluid in my 2500 Tow Pig pickup today. ONLY 285,000 miles on this rig. Just 40,000 on the diff fluid. The level was spot on after 40,000 miles. I just completed a 1300 mile trip, 650 miles towing a 9,000 pound enclosed trailer. It has a real differential that holds 3 quarts or 7.5 xs my Cx 5. It tows about 10 times the weight of a CX 5. Not that I ever expected our CX 5 to be a tow pig.

I have friends with over 400,000 miles towing on these truck diffs. The owner's manual call out changing the differential and transmission fluids. Could be Mazda is trying to reduce its's carbon footprint at the owners expense by not recommending trans and diff fluid changes......!

So much for Japanese quality being superior vs USA....

Concerning comparing the differential oil capacity of the CX-5 to your domestic truck… the Mazda is just a differential, but doesn’t the truck's differential oil fill out the left/right axle tubes to lubricate the axle bearings?

 

[AL Cx5]

Concerning comparing the differential oil capacity of the CX-5 to your domestic truck… the Mazda is just a differential, but doesn’t the truck's differential oil fill out the left/right axle tubes to lubricate the axle bearings?

Yes the truck axle bearings are in this diff fluid, live axle design. The CX 5 diff has bearings in diff fluid as well but close to the gears, IRS. THEN two more bearings in the hubs. Without a doubt the old tech live axle design is simpler and longer lasting.

I'll get some comparative photos of the massive cast iron 2500 truck diff vs the Mazda light duty aluminum gearbox. I'm comparing a tow pig to a "soccer Mom" SUV. TWO different categories. One made for heavy loads and last the other to zip around in, then trade it. The CX 5 cost of ownership is much, much higher. That may or may not be important to folks who have been programed to make monthly car payments or leases.

Our CX-5 maybe long gone and the 2500 truck will still be doing it's tow pig thang. It will be 20 years old in 2026. Engine will go +400,000 miles before a rebuild, trans 250,000 miles or more.

There main point, maintain the CX 5 like a 2500 truck, NOT like Mazda suggests and avoid differential and trans failures. I'm generally impressed with the quality of our CX-5. Forged crankshaft and rods got my attention. OCD attention to wiring and other details is another. Open ECU tuning sealed the deal. Little did I know we have to deal with MazdaEdit...LOL

It's criminal the light duty market has become a throw away vehicle market. Manufactures purposely miss lead uneducated owners how to maintain their vehicles. Life of the vehicle fluids should be a massive class action lawsuit...

 

[BoomerZoomr]

It’s still apples to oranges comparison… but comparing a recent production Mazda to recent production Ford, Ram or General Motors trucks, those domestic trucks have some engineering debacles that are inexcusable.
Not sure what you mean by high cost of CX-5 ownership. We had three Toyotas, and basically only paid for routine maintenance/wear. This CX-5 is the third Mazda I have purchased, and I expect the reliability to be comparable to the Toyotas. Let’s hope anyway.