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Discussion Starter #1
My 2014 has 57,000 miles. The Scheduled Maintenance says to change the rear differential oil after 30,000 if it used in harsh conditions; of which I have very few miles. Other than that, it does not say it needs to be changed ever. That seems odd. What is the truth here?

I have a letter stating that there is a Special Service Program extending the warranty on Power Transfer Unit to 90,000 miles. It says that if I am not having problems I don't need to do anything. Is the Power Transfer Unit the same as the Rear Differential?

I expect to put more than 90,000 miles on it eventually. Does it get any maintenance, ever?

Thanks
 

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In your vehicle manual it states what driving conditions would imply which maintenance schedule you should follow. Now a lot of manufactures will state things like "sealed for life" or maintenance free for some components which I call "BS". Everything deteriorates be it the lubricant or mating surfaces. There is not such thing currently of any component that won't wear out over time or use found in our cars, otherwise how would manufactures make money off of repairs. Also the idea of "sealed for life" assumes that people would get a new car by the time these components will fail. Despite what it says I personally would get these fluids changed at there respective "severe condition" schedule as we follow here in WI, which I assume being upstate NY follows the same schedule. And yes both the differential and transfer case uses the same oil just different amounts. Save yourself future cost of a new unit and change the fluid. Way cheaper than a new transfer case or rear differential.

Our CX3s (as well as the new CX 9) takes a fancy hypoid oil thingy that is really expensive (the differential only uses a little over a pint) and currently at a dealer level anyway no cheaper replacement like how 15' and older awd cars uses any 80w90 lube. For the CX 3 you need to change the diff and transfer case lube every 30k which is the same for the CX 5 and CX 9.
 

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Discussion Starter #3
Okay, I get that you recommend changing the oil.
But are the rear differential and the power transfer unit two distinct items?
The 30,000 miles of severe conditions is for the rear differential. The power transfer unit isn't mentioned at all; I only know about it because of the warranty extension letter.

I normally use a private garage for oil changes and the like. Would changing these oils be better at a dealer?

Thanks for your help.
 

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They are two different components. The transfer case is mated next to the transmission in the front of the vehicle. It connects the drive axles of the front wheels with the rear wheels via a driveshaft to rear differential. The rear differential is the little "box" in the back that connects the rear wheels by cv axles that then is connected to the driveshaft to the transfer case to the transmission.

The only thing to look out for is using the correct type of oil needed for both the differential and transfer case as prior to the 2015 models, we used bulk sale Shell 80W90 oil. For the new 2016 CX 3, 5, and 9 all use this new hypoid gear oil thing that we currently have not found an allowable substitute as the mazda hypoid oil thing is really stinkin expensive. So until then even myself will be forced to use the expensive oil unless an alternative is allowed which would be cheaper. I also would have to change my rear diff oil and transfer case oil sooner, probably be doing it at around 20k or such as I check both oil conditions every oil change, seeing as one I drive short distances, drive pretty "sporty", and drive in bonkers weather (hot summers, cold salty miserable winters, and crazy flooding springs).
 

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Discussion Starter #5
Right now I am talking about my wife's 2014 CX9. it will take me a 5 years to get 30,000 on my CX3.
You recommend changing both the the rear differential and the transfer case oil, even though the transfer case isn't mentioned in the maintenance schedule?

Anything else that isn't mentioned in the schedule?

Can I trust this to the garage, or should I go to dealer? I like the mechanic, but he may never have done it before.

You are in Madison, right? My son just moved there, one block from Lake Manona. Incredible to have a lake like that in an urban area.
 

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My reasoning for changing out the transfer case stems from what I was taught in Tech School where I learned to be a entry level tech. The transfer case has moving parts just like the rear differential and as such that fluid will break down. Theres no harm in changing it out either, just make sure you get the right stuff for it.

Any mechanic that has touched a 4wd or awd system will know how to put in fresh fluids.

Theres nothing else that comes to mind for other unmentioned maintenance. Every 30k change out the differential and transfer case fluids, @ 60K change spark plugs which on your V6 is a pain (also found in the old 6s and tributes), 100k-120k coolant flush, and I dont remember when automatic trans flush is but usually pass 100k or if the dipstick looks gross for it. Its also not a bad idea to always flush and fill brake fluid when doing brakes which usually get changed every 50k to 60k but doing a period check of its condition is better as sometimes the brake fluid is still good after 50K+ miles. Also if doing spark plugs on any V6, it is usually recommended to replace the 3 rear ignition coils since one its a pain to get to and two they tend to fail due to oil starting to seep and pool in the spark plug hole damaging the coils (Mazda/Ford V6 quirks) and one PCV as during disassembly the valve may break (crappy plastic) as it is required to remove that valve as its in the way.

I live out in the west side of Madison near the West Towne Mall area which is also near the Don Miller Mazda dealership where I work. I used to live in the downtown area when I first moved here to Madison.
 

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When you drain the diff, you drain the clutch (PTU) and they only take half a litre (about a pint) so even if the oil is expensive, it won’t break the bank. Toyota use a very similar unit and they have a fixed 2 year or 20,000 mile service period which I will use. The oil usually comes out quite grubby because it caries the wear debris from the little multi plate clutch.
 

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Actually anchorman funny enough, in a dealer setting at least for us we can't just bill out 1pt of this hypoid gear fluid as our system only recognize it as 1qt (comes in mazda qt bottles). So although it may only need 1pt of fluid we unfortunately have to bill them the whole qt. That is why we are trying to see what recommended substitute we can get in drums as so we can bill out in pints instead of quarts. If I remember right its about $80 USD for a quart of that new stuff compared to the 80W90 Shell oil we use at $6 for a pint.
 

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Actually anchorman funny enough, in a dealer setting at least for us we can't just bill out 1pt of this hypoid gear fluid as our system only recognize it as 1qt (comes in mazda qt bottles). So although it may only need 1pt of fluid we unfortunately have to bill them the whole qt. That is why we are trying to see what recommended substitute we can get in drums as so we can bill out in pints instead of quarts. If I remember right its about $80 USD for a quart of that new stuff compared to the 80W90 Shell oil we use at $6 for a pint.
Any chance you want to come work for a Mazda service shop closer to Chicago? That kind of customer-centric approach is sorely lacking here.
 

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Discussion Starter #10
For my CX-9 2014...

The local dealer service finally got back to me.
He agrees that it would save significant labor to replace the rear coils at the same time as the spark plugs, but they have never had to replace a coil, so he figures it would be false economy to replace 3 coils at $150 each just to save $150 labor.
He doesn't know what I am talking about the PCV for, it is right up front and easy to replace if it is ever necessary.
The transfer case is not considered serviceable; they have never changed the oil on one. They replace a lot under warranty, but don't change the oil.

I have read on the internet about people pumping oil out of the transfer cases and finding it really bad. But I expect doing that privately might void the 90,000 mile warranty on it.

So confusing. Should I try another dealer?
 

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For my CX-9 2014...

The local dealer service finally got back to me.
He agrees that it would save significant labor to replace the rear coils at the same time as the spark plugs, but they have never had to replace a coil, so he figures it would be false economy to replace 3 coils at $150 each just to save $150 labor.
He doesn't know what I am talking about the PCV for, it is right up front and easy to replace if it is ever necessary.
The transfer case is not considered serviceable; they have never changed the oil on one. They replace a lot under warranty, but don't change the oil.

I have read on the internet about people pumping oil out of the transfer cases and finding it really bad. But I expect doing that privately might void the 90,000 mile warranty on it.

So confusing. Should I try another dealer?
Its hard to say seeing as you can wait till near the end of your warranty to do the fluid change and extend the life of your transfer case pass the warranty period or you can hope for the best.
Replacing the 3 coils is just what we recommend as our shop at least find oil and at least 1 coil fail back there. But it is up to the customer to perform replacing those coils. That pcv valve is the little plastic elbow piece near the intake boot. Those tend to crack fairly easily after some time has pass and I just recommend to have it just in case (so far I've done a few V6s and haven't broken those valves *knock on wood*).
 

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Any chance you want to come work for a Mazda service shop closer to Chicago? That kind of customer-centric approach is sorely lacking here.
Haha, well the dealer here refuse to let me leave for that very reason among other reasons so no luck there buddy. I have my own "opinions" on some Illinois dealers there from when we get their cars or their dealer traded cars...:|. I find it a lot easier to teach a customer instead of telling the customer arbitrary things about their cars. I am more than willing to sit with them and explain their car parts, explain their electronics, bring them into the shop and show them what is wrong, potentially wrong, things to look forward too in the future in terms of repair, and so on. A well informed customer is a smarter customer. I applied this same thing when I worked in retail for a number of years. It probably comes from the fact that I'm originally from Hawaii and if I were less than "customer-centric" there is a good chance they might know a relative of mine and then I get in trouble in some form. In Hawaii someone knows someone and I've been conditioned to make sure I don't bit in the butt.
 

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Discussion Starter #13
Replacing the 3 coils is just what we recommend as our shop at least find oil and at least 1 coil fail back there.
I wish I understood cars better; at times I just feel helpless.
Are you saying you replace the coils routinely when you change the spark plugs, or just when you find oil on them? Is the oil a symptom of failure, or does it cause failure?

I really appreciate your help.
 

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We tell customers that its mostly preventative, but we try to urge customers to replace them when we do find a fair amount of oil in the spark plug cavity. The oil can contaminate the coils and this is just a fault of the engine itself (ford influenced).

I recommend getting a full quote for the job and judge from there. I can't really say if you should really do it since I would perform the job myself and save me the labor cost regardless if I was a tech or not (its just how I am).
The other reason if I remember correctly is that the rear coils are heat soaked more than the front 3 so that increases the chances of the coils failing as we have had a few CX 9s and 6s come in for damaged rear coils due to heat (just doesnt get very good air flow back there). I recommend to do the spark plugs since it needs to be done regardless, but the coils is up to you.

Just to be clear that my shop merely recommends and do not force the customer to do a job they feel they dont need to do. Everything we quote is based on past experiences.
 

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Discussion Starter #15
I called two more dealers. They both agreed with changing the transfer case oil (which the first dealer said there was no procedure for) and both said that I shouldn't change the coils unless I was having a problem.

So I am going with one of the other dealers. He is cheaper and will give us a loaner for two days, so the fact that he is much further away is not a problem.

Again, I appreciate your help. I certainly wouldn't have changed the transfer case oil without it.
 

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Discussion Starter #16
I got my 2014 CX9 back today. They DID'T change the transfer case oil. It is a sealed unit and the oil can't be changed. They did the other work, but not the transfer unit. That is the same as what the first dealer told me.

I hear you telling me it should be changed, and other people on the internet saying they have done it and the oil gets pretty gamy by 50,000 miles.

However, Mazda has extended the warranty on the part to 90,000 miles. If telling people to change the oil would prevent warranty repairs, it seems to me that they would do it. Even if they don't care about us, wouldn't they do what saves them money? I am afraid that changing it might void the warranty.

It is all so damned confusing.
 

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Discussion Starter #17
I emailed Mazda, asking them their policy on the transfer case oil.
They say it can be changed; the dealers were probably thinking of the 2015 that cannot be changed.
They only recommend it IF the dealer says it is necessary.

We are going on a big trip next week and I would hate to have the car break down because of this. What happens when it fails? Does it just break and leave you stranded, or does it deteriorate over a few weeks, or what?
The recall notice says it can leak under high speeds or heavy loads; which we don't have much of.

I am wondering whether to panic and get it done (the nearest dealer willing to do it is 90 minutes away and I don't really have time for that now) or if I should just try and get it done at the next oil change. I have 58,000 miles now.
 

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Discussion Starter #18
Actually I was in the middle of forwarding the Mazda email to the dealer who didn't do the work, when i noticed she referred to transmission fluid. I called to ask if she used the wrong word, or was talking about the wrong part; as i had asked about the transfere case.
She came back after putting me on hold, to say that it is a sealed unit, but dealers can change the oil if they want. That is all she would say; beyond that it was up to the dealer. ARGH!
 
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