2021 CX-9 Burning oil

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2021 CX-9 Sig
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2021 CX-5 GT
It sounds like what's happening is as the oil gets older it is getting thinner(either the oil is breaking down or their is gas in the oil so a Blackstone UOA might be needed) and working past the seals after the 4k/5k mark.

If i was OP, would change oil (or have a local mechanic do it so you have a record, get Blackstone test on the used oil, take pictures of your dipstick after car sat overnight, make sure dipstick is at the line an don't overfilled....if so, drain some out and then take picture of dipstick with date/time stamp, drive CX9 for 5000 miles and check oil level, if down take to dealer and get them to fix it.

I have never had to add oil to a new engine/ new car between oil changes until the car was really old( 12 to 14 years) and started to burn some oil.

For them to say, yeah well test it after 2000 miles is crazy. Especially when oil changes are every 5000 to 7500 miles.
Unless you have a leak in the oil pan or a completely f'd up engine, no engine is gonna burn that much oil in 2000 miles.

They clearly are treating you like some young niave person. They usually treat most people like idiots because most of the population is not mechanically knowledgeable.

I think you are 100% right. I also think that longer, more sustained driving burns the oil much faster.
 

Jack Rabbit

Banned
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18 Mazda CX5 AW
Agree on the oil getting thinner. But I don't think there is gas in the oil since the car has only 16K miles on it.
The recommended oil is already thin when brand new. The oil is probably breaking down, and becomes thinner. Based on members saying the oil doesn't drop until after the 4000/5000 mark, the defective seals probably work very well with new oil until the oil runs for a couple thousand miles.
But who wants to change oil every 4000 miles??? I change mine every 6000 to 7000 and that's difficult when busy.
 
The recommended oil is already thin when brand new. The oil is probably breaking down, and becomes thinner. Based on members saying the oil doesn't drop until after the 4000/5000 mark, the defective seals probably work very well with new oil until the oil runs for a couple thousand miles.
But who wants to change oil every 4000 miles??? I change mine every 6000 to 7000 and that's difficult when busy.
Agree, and my Mazda dealer here in NJ is recommending oil change every 5K miles
 
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Northeast
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2020 CX-5 Tour
I have repeatedly mentioned this in posts through this thread but the strange thing is that if you check at any point below 4K miles, everything looks fine. After that, from 4K to 5K, the levels drop dramatically.
I did remember what you had reported previously when I read what @asatar22 posted, and it gave further confirmation to what you had already discovered with all three of your vehicles. And just a few minutes ago, I finally thought of something that might make some sense out of all of this - at least to me anyway.

Right from the start of this, I've been wondering if the 'defect' with these seals was that they're undersized by a VERY small amount. The seals would only need to be too small by a miniscule margin, in order for some oil to get past them. And the under sizing could have happened as a result of either a miscommunication with the new supplier, or simply a production sizing error. And it's also painfully obvious that the error wasn't detected at any point in the QC process.

The new piece of the puzzle that I just ceme up with is the idea that the oil companies might be including in their additive packages, some small amount of the same seal conditioner that they use (probably more of) in their 'high mileage' oils, which causes worn seals to expand. And if that's correct, then it's also reasonable to assume that this seal conditioner, as with most additives, would lose effectiveness after a number of miles.

So this complete picture would be slightly undersized seals installed at the factory, expanding for 4K or so miles as a result of being in contact with the seal conditioner additive, and then reverting back to their original size, after the vehicle travels that 4K+ miles and the seal conditioner effectiveness is greatly reduced.

Yes, this is all pure speculation, but one nice thing about a forum is that everyone gets to have an opinion.
 

ctbale

Member
Contributor
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2022 CX9 Tourin
I did remember what you had reported previously when I read what @asatar22 posted, and it gave further confirmation to what you had already discovered with all three of your vehicles. And just a few minutes ago, I finally thought of something that might make some sense out of all of this - at least to me anyway.

Right from the start of this, I've been wondering if the 'defect' with these seals was that they're undersized by a VERY small amount. The seals would only need to be too small by a miniscule margin, in order for some oil to get past them. And the under sizing could have happened as a result of either a miscommunication with the new supplier, or simply a production sizing error. And it's also painfully obvious that the error wasn't detected at any point in the QC process.

The new piece of the puzzle that I just ceme up with is the idea that the oil companies might be including in their additive packages, some small amount of the same seal conditioner that they use (probably more of) in their 'high mileage' oils, which causes worn seals to expand. And if that's correct, then it's also reasonable to assume that this seal conditioner, as with most additives, would lose effectiveness after a number of miles.

So this complete picture would be slightly undersized seals installed at the factory, expanding for 4K or so miles as a result of being in contact with the seal conditioner additive, and then reverting back to their original size, after the vehicle travels that 4K+ miles and the seal conditioner effectiveness is greatly reduced.

Yes, this is all pure speculation, but one nice thing about a forum is that everyone gets to have an opinion.
Definitely some excellent points you brought up. It gets me thinking about what they actually did and then undid for this problem. The seals are not exposed to any "oil pressure" from the pump. Its just splash oil. There are pressures on the non oil side from the intake manifold and exhaust ports. But those pressures are mitigated by the relatively tight clearance between the valve stem and the guide bore. There are millions of engines out there in the world that don't even have valve stem seals. So I guess what I'm saying is the seals don't experience severe duty. Unless you want to take into consideration the heat which is probably pretty high. My gut feeling says they just switched vendors. The words in the tsb says valve stem seal modification so it's kind of vague. It's a Japanese company with Japanese practices so they're not going to blurt out anything that would make them look bad.
 
Definitely some excellent points you brought up. It gets me thinking about what they actually did and then undid for this problem. The seals are not exposed to any "oil pressure" from the pump. Its just splash oil. There are pressures on the non oil side from the intake manifold and exhaust ports. But those pressures are mitigated by the relatively tight clearance between the valve stem and the guide bore. There are millions of engines out there in the world that don't even have valve stem seals. So I guess what I'm saying is the seals don't experience severe duty. Unless you want to take into consideration the heat which is probably pretty high. My gut feeling says they just switched vendors. The words in the tsb says valve stem seal modification so it's kind of vague. It's a Japanese company with Japanese practices so they're not going to blurt out anything that would make them look bad.
I think they switched vendors and the seals either of bad material quality which degrades with usage, or nothing wrong with the seals material, but the manufacturing process, size, how tight they are, etc. might not be accurate. I am ok with the latter since it means the problem will not get worse overtime, it will stay as is and the oil burning rate will remain the same(light goes off every 4700 Miles). If the seal materials is the culprit then the problem will get worse overtime which requires fixing all impacted vehicles in timely manner.
 

ctbale

Member
Contributor
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2022 CX9 Tourin
I think they switched vendors and the seals either of bad material quality which degrades with usage, or nothing wrong with the seals material, but the manufacturing process, size, how tight they are, etc. might not be accurate. I am ok with the latter since it means the problem will not get worse overtime, it will stay as is and the oil burning rate will remain the same(light goes off every 4700 Miles). If the seal materials is the culprit then the problem will get worse overtime which requires fixing all impacted vehicles in timely manner.
I would expect the worst case. If it was my engine, I would want all those seals out of there.
 
I would expect the worst case. If it was my engine, I would want all those seals out of there.
Its a lease, so I will return it in 15 months. Also I might sell it to carmax to make some money 3 months before lease end. If it was my car(finance not lease) probably I would have been more worried by now😁. Lets wait for feedback from people who did the fix, if all is good I would go for it. I had plans to purchase the car and keep it for another 3 years past lease end if the CX-90 turned out to be way more expensive. However, this issue forced me to change plans, but if the fix turned out to be ok I might still keep it.
 
I have about 33k miles on my 2021 CX-9. The VIN is in the range of vehicles affected by the oil burning issue. I have been doing oil changes anywhere between 4600 and 5300 miles, but have never had low oil issues. Do all of the vehicles in the VIN range have (or will have) this problem or am I just lucky and my engine is not burning oil?
 
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Mazda CX-9 Signature
I have about 33k miles on my 2021 CX-9. The VIN is in the range of vehicles affected by the oil burning issue. I have been doing oil changes anywhere between 4600 and 5300 miles, but have never had low oil issues. Do all of the vehicles in the VIN range have (or will have) this problem or am I just lucky and my engine is not burning oil?
I would measure the oil level after oil change and measure again before next oil change. This way you can visualize if your engine is consuming oil.
 
Yes. Best time is in morning before you start vehicle.
I'm 3k since my last oil change and the level is at the lower hole on the dipstick. I snapped a picture and will add a quart. If I keep tracking the level and mileage and take pictures, will this be enough for the dealer to open a claim? Do they need more evidence, like the low oil light? I really would rather not run it low. I do a lot of highway driving.
 
I'm 3k since my last oil change and the level is at the lower hole on the dipstick. I snapped a picture and will add a quart. If I keep tracking the level and mileage and take pictures, will this be enough for the dealer to open a claim? Do they need more evidence, like the low oil light? I really would rather not run it low. I do a lot of highway driving.
They need the light to come on and throw a code to perform the TSB. Wondering if you unplug the oil pressure sending unit for a minute would do it.
 
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Mazda CX-9 Signature
I'm 3k since my last oil change and the level is at the lower hole on the dipstick. I snapped a picture and will add a quart. If I keep tracking the level and mileage and take pictures, will this be enough for the dealer to open a claim? Do they need more evidence, like the low oil light? I really would rather not run it low. I do a lot of highway driving.
I do think it's best for dealer to visually confirm and document the issue than for you to document it on your own.
 

Jack Rabbit

Banned
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18 Mazda CX5 AW
I do think it's best for dealer to visually confirm and document the issue than for you to document it on your own.
Or better yet. Do both. Have them document and you document as well. However I would change the oil myself, let sit overnight, recheck and make sure not overfilled before take it to dealership.
 
Or better yet. Do both. Have them document and you document as well. However I would change the oil myself, let sit overnight, recheck and make sure not overfilled before take it to dealership.
I think it should be easy, when the light goes off don't top it. Drive it with the light on to dealership so they would see the light and the code. Usually when the light comes on I am busy and in the middle of something so I top it off and go to dealership later.
 
They need the light to come on and throw a code to perform the TSB. Wondering if you unplug the oil pressure sending unit for a minute would do it.
That's what I figured. I expect the light to go off in the middle of nowhere on the highway. If that happens, I'll just take a picture of the instrument panel, pull the code with the bluetooth reader I have, and top it off. If I'm in town, I'll drive over with the light on.
 

Jack Rabbit

Banned
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18 Mazda CX5 AW
That's what I figured. I expect the light to go off in the middle of nowhere on the highway. If that happens, I'll just take a picture of the instrument panel, pull the code with the bluetooth reader I have, and top it off. If I'm in town, I'll drive over with the light on.
But ... And heres the catch....if you top it off, will they use that as an excuse to say nothing wrong with it, just a code malfunction, take the vehicle in back, reset the unit and send you on your merry way??? This is chess, not checkers!
 
That's what I figured. I expect the light to go off in the middle of nowhere on the highway. If that happens, I'll just take a picture of the instrument panel, pull the code with the bluetooth reader I have, and top it off. If I'm in town, I'll drive over with the light on.
You don't need the light to be on, just that it sets a code. That is the criteria. You can tell them the light came on and show them a pic if you want but you need the code stored. You could have been due for an oil change when it came on or just did an oil change early and have clean oil when you bring it in. It's not their business how soon you like to change your oil as preventative maintenance. Only the code needs to be set when you bring it in. It's not rational or expected that someone drive around with a low oil light on the dash and possibly do engine damage until they can get to or make an appointment and bring the car into the dealer!