2.5 Turbo - Oil Fuel Dilution Issues?

V
Mazda CX-9 Grand Touring 2016
The oil happened to be a cheap Castrol GTX magnatec. If I understand correctly, it should not affect fuel levels? Better oil should have just maintained the viscosity better.
Possibly more relevant fact was that I ran only 87 gas this time, as a low interval experiment
Switching to 91 and AmsoilOE, will check again in 3500.
Nothing wrong with the GTX Magnatec.
Of course it will affect the oil level. If nothing else changes, the volume of liquid in the sump will be 5% greater.
Better oil has nothing to do with the viscosity of the oil & gasoline mixture. Dilution is dilution.
91 AKI & Amsoil oil is money spent that is not addressing the problem with this engine. The possible causes of fuel dilution are stated in the report. The cause of the dilution in your engine needs to be found and fixed.

I think the high tire inflation pressure is to prevent bouncing and possibly loosening the lashings while aboard the ship. A couple of weeks on a ship's deck is no different for flat spotting that two weeks stationary in a dealer's lot.
 
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V
CX-9 GT 2019
I probably misspoke. I don't consider GTX Magnatec bad (i would not buy it if so) and by cheap I did mean one of the cheapest top-brand options in Full-Synthetics. And therefore I did not expect any margin from it if anything is not good. In comparison, there is some consistent evidence on WRX forums that top dollar 5w-30 (Mobil ESP specifically) maintains viscosity better when there is a fuel dilution. I don't have oil dilution issues on my WRX, so I can't confirm.

Main question now is... How to even approach the problem? The car is on warranty, how to make the dealership to investigate? Does the oil analysis stands as an acceptable reason for a warranty claim? Otherwise the car starts,drives,idles perfectly.
 
V
2010 CX-9 GT
I probably misspoke. I don't consider GTX Magnatec bad (i would not buy it if so) and by cheap I did mean one of the cheapest top-brand options in Full-Synthetics. And therefore I did not expect any margin from it if anything is not good. In comparison, there is some consistent evidence on WRX forums that top dollar 5w-30 (Mobil ESP specifically) maintains viscosity better when there is a fuel dilution. I don't have oil dilution issues on my WRX, so I can't confirm.

Main question now is... How to even approach the problem? The car is on warranty, how to make the dealership to investigate? Does the oil analysis stands as an acceptable reason for a warranty claim? Otherwise the car starts,drives,idles perfectly.
I would at least take the car into the service department and share the results of the UOA with them. At a minimum, it will start a warranty claim/history that you can point back to in case something fails later. I don't know if the dealer will act on one UOA, you might need several to prod them into action.

The quickest test to do is a compression/leakdown test to see if you actually have blow by. You could also do a fuel injector leak down test to see if an injector is leaking.

Good luck.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg. Plano, TX
Contributor
L
Plano, Texas, USA
V
16 CX-5 GT AWD Tec
I probably misspoke. I don't consider GTX Magnatec bad (i would not buy it if so) and by cheap I did mean one of the cheapest top-brand options in Full-Synthetics. And therefore I did not expect any margin from it if anything is not good. In comparison, there is some consistent evidence on WRX forums that top dollar 5w-30 (Mobil ESP specifically) maintains viscosity better when there is a fuel dilution. I don't have oil dilution issues on my WRX, so I can't confirm.

Main question now is... How to even approach the problem? The car is on warranty, how to make the dealership to investigate? Does the oil analysis stands as an acceptable reason for a warranty claim? Otherwise the car starts,drives,idles perfectly.
IMO you can at lest start to check oil level more often and see if the oil level is rising. Once your next UOA is back and if it till shows too much fuel, you definitekly take 2 UOA reports to your Mazda dealer.
 
V
CX5 GT +pp 2018
We need more UOAs to make any conclusions. Could be the driving stye, could be fuel, could be anything.

...And I still believe fuel and oil plays a certain role contrary to popular opinion that it does not matter.
 
V
CX-9 AWD GT Titanium/Sand
How many miles on your CX-9?

There're several reports in CX-5 forum that the oil is over-filled from factory on their 2.5T. And using 87-octane gas should have nothing to do with oil dilution issue. Try to use Top-Tier gas all the time though.

For SkyActiv-G 2.5T turbo you don't get better performance with 93-octane premium gas unless you rev your engine over 4,000 rpm. For most 2.5T owners using premium gas is a waste of money.
About 2k miles now.

Luckily I don't think I have the oil dilution problem, at least not now.
Turned the engine on to warm up for few minutes, turned it off and let it stand for 2 min, checked oil level and it was exactly in the middle between low and high. I don't smell gasoline, it's relatively light and has the right consistency.

The '17 CRV we had I noticed the problem on the first oil change after 3.5K miles. Oil level was about half inch over the max, it was black, think like water and reeked of gasoline smell.
 
V
CX-9 AWD GT Titanium/Sand
Not this again.
Tires are overinflated before shipping, to prevent flat spots from developing while on the boat. Most of us on here know that.
Checking tire pressures is part of the dealer prep checklist that's supposed to be done prior to delivery to the customer.
If the tires are still overinflated, it means your dealer tech rep was lazy, cutting corners, and didn't do their job during the prep.
He probably just looked at them, decided they were OK, and put his checkmark next to "tire pressure checked" on the list.
Stuff like this really ticks me off.
I know... it pisses me off, too. You don't know how many times I asked the dealer to provide me copy of the prep checklist.. and I never got it. Obviously some prep was done, or stuff wouldn't work, but apparently not the tires... And at that point even if I got a copy, I'm sure it would've been made to look like all was done.
 
V
CX-9 AWD GT Titanium/Sand
Main question now is... How to even approach the problem? The car is on warranty, how to make the dealership to investigate? Does the oil analysis stands as an acceptable reason for a warranty claim? Otherwise the car starts,drives,idles perfectly.
In my experience, service may use any lies to negate your findings. But demand them to acknowledge the problem when it comes up again, and take details records of your visit.

Main 2 things you should do at this point:
1) Open claim with Mazda directly. This is the date from which lemon law case will count.
2) Get a good lemon law attorney. I can give you mine that helped with our CRV, but he's in PA, and you're in WA, so not sure he can help.
 
V
Mazda CX-9 Grand Touring 2016
Yep, open a warranty claim. 5% fuel dilution at 3350 miles is a serious matter. If you wish, make an appointment to sit down with the service manager, not just one of the service writers. Don't tell them how to do their job, but do tell them that you want this serious problem repaired. My initial thought is that they'll just replace the four injectors and send you out the door. That might not be their method at all. Let them decide. You shouldn't have to bear the cost of future oil analyses, but you probably will have to. The analysis doesn't show problem levels of wear metals in the oil sample, so the engine should be fine. The titanium is most likely from the anti wear additive sold by Afton Chemical that is a highly effective and lower cost substitute for the molybdenum compounds that are widely used.
 
V
2016 CX9 GT AWD
Causes for fuel dilution include one or more of these factors...

Poor injector performance, i.e. poor atomization causing incomplete combustion.

Poor fuel metering. Pump/sensors delivering too much fuel, fuel trickling in when engine stopped.

Blowby. Generally speaking, the more boost the more blowby.

Cold engine/not reaching operating temps on short trips.


When you first start the engine the engine is running rich.
You can see this by look at your MPG indicator, you will have terrible mileage for the first few minutes no matter how light you are on the throttle.

During this time there is going to be unburned fuel in the charge that becomes part of the blow-by.
Mash the pedal down and get boost plus cold engine, more fuel in the blow-by.
Make lots of short trips with a cold engine, more fuel in the blow-by.

As for the 87 vs. 93 octane thing...the engine is controlling parameters to prevent detonation with the lower octane and maximizing performance and boost with higher octane.
So in theory if the fuel dilution is related to blow-by, there should be LESS dilution with 87 octane than 93 octane, unless there is some other engine control factor I'm not taking into account.

So if the engine is operating properly, the driving conditions would be the next thing to examine.
It would also be interesting to see a winter vs. summer UOA.

As for the drop in viscosity...an SAE 30w oil has to have a min viscosity of 9.3 and a max of not more than 12.5 cSt.
So that 8.3 is alarming but seems inline with used oil with 5% fuel dilution.
The low water and soot levels would seem to indicate that things aren't running rich and that the engine is getting up to operating speeds regularly.
That would seem to indicate a mechanical cause for fuel dilution.
 
V
2016 CX9 GT AWD
IMO you can at lest start to check oil level more often and see if the oil level is rising.
That isn't necessarily going to be a good method of tracking fuel dilution, unless it is severe.
With a 4.8l engine oil capacity, 5% dilution is about 250ml or 8.5oz, IF you have burned no oil or added water or other contaminants.
If you burn some oil and add gas, the level might not change much if at all.

I still advocate checking, just be aware it isn't a good indicator, beyond maybe smelling fuel in the oil.
 
V
CX-9 GT 2019
OK, 3.8% in 2.1k.



Difference:

1 sample:
- winter, jan-june
- 60% short, non-highway trips
- Regular gas
Oil level dropped alot after first 2k. Had to add 1q, then stable. Never seen it going up.

2 sample:
- all-summer
- 70%+ highway
- Premium gas
Oil level possibly a bit up at the end. Mid-level after fill, a bit above middle at sample.


Haven't had a chance to open a claim yet, now I plan it in couple of weeks.

I was a bit skeptical after 1st sample. I have been changing oil and sampling 3 other turbo engines in last few years. None had oil dilution. And with this one I don't notice any difference in smell etc... I kind of expect it to be obvious if it is that severe. This sample adds some confidence :)
 

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V
2018 CX-9 SIGNATURE
OK, 3.8% in 2.1k.



Difference:

1 sample:
- winter, jan-june
- 60% short, non-highway trips
- Regular gas
Oil level dropped alot after first 2k. Had to add 1q, then stable. Never seen it going up.

2 sample:
- all-summer
- 70%+ highway
- Premium gas
Oil level possibly a bit up at the end. Mid-level after fill, a bit above middle at sample.


Haven't had a chance to open a claim yet, now I plan it in couple of weeks.

I was a bit skeptical after 1st sample. I have been changing oil and sampling 3 other turbo engines in last few years. None had oil dilution. And with this one I don't notice any difference in smell etc... I kind of expect it to be obvious if it is that severe. This sample adds some confidence :)
Curious to see how this turns out. Thanks for the info.
 
V
Mazda, 2016 CX-9 Signature
I have been looking at these posts for awhile. I don't drive my CX-9 much. I just turned 20,000mi and it will be 3 years old Feb 1st. I never noticed anything wrong until I checked the dipstick last week and it was definitely over full and had a gas odor to it. I took a sample and just put it in the mail today. So I will have to keep you posted on this. i would recommend all of you to keep an eye on your oil level since mine just just had an issue at 20,000mi.
 
V
Mazda, 2016 CX-9 Signature
Well just got my analysis back from Oil Analyzers and it showed the fuel dilution as 4 which is critical and there is a little loss in viscosity. I guess I will be making a trip to the dealer. Has anyone taken there car to the dealer for this problem? I would like to know what your dealer said. Thanks
 

Cuz

Contributor
This can*t be just a CX-9 issue. The 2.5 turbo is in multiple vehicles. Anyone seeing it show up in the other vehicles ?
 
V
CX-9 GT 2019
I would at least take the car into the service department and share the results of the UOA with them. At a minimum, it will start a warranty claim/history that you can point back to in case something fails later. I don't know if the dealer will act on one UOA, you might need several to prod them into action.

The quickest test to do is a compression/leakdown test to see if you actually have blow by. You could also do a fuel injector leak down test to see if an injector is leaking.

Good luck.
Made a trip to the dealership. As I expected, they were useless. They wanted to get away with oil change :)

They asked questions like:
"Why do you think it's an issue..."
"What is the Mazda spec for viscosity... it is degrading over 5k interval anyways"

When I asked for some diagnostics for injectors:
"Injectors are controlled by computer, it is very precise and if anything not right you will get CheckEngine..."

Basically, they only checked if ECU firmware is latest and it was latest.
And useless visual check. That's it.

Everything, including oil analysis were captured in history.

Can someone please help with next steps and with the question:
How can I emphasize the seriousness of the issue to them or which diagnostics they HAVE TO BE ABLE to do so I can ask specifically?
 
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V
2010 CX-9 GT
Made a trip to the dealership. As I expected, they were useless. They wanted to get away with oil change :)

They asked questions like:
"Why do you think it's an issue..."
"What is the Mazda spec for viscosity... it is degrading over 5k interval anyways"

When I asked for some diagnostics for injectors:
"Injectors are controlled by computer, it is very precise and if anything not right you will get CheckEngine..."

Basically, they only checked if ECU firmware is latest and it was latest.
And useless visual check. That's it.

Everything, including oil analysis were captured in history.

Can someone please help with next steps and with the question:
How can I emphasize the seriousness of the issue to them or which diagnostics they HAVE TO BE ABLE to do so I can ask specifically?
You will either have to go to a different dealer or call Mazda corporate and talk to someone there. If the service manager, whose job relies upon knowing what is acceptable, can't be bothered to determine what Mazda's specs for viscosity are I don't have much faith that things are going to progress at that dealer.

Somewhere in the owners manual will be a phone number to contact a regional manager. Start there. You need to be polite and state that you are concerned about the engine in light of the multiple oil analyses showing fuel dilution. Hopefully, they will give you a case number and contact the dealer so the information can be forwarded up the chain. I'd ask the regional manager the questions the dealer asked you: What is Mazda's position on acceptable fuel dilution and viscosity degradation?

New 5w30 oil should have a viscosity above ~9.2 at a minimum at 100C (and less than about 12.5). You could try to find 5w30 oil with a relatively high starting viscosity to buy yourself a little more time. I haven't been on "Bob is the Oil Guy" forums in many years, but I know I've seen data on the viscosity of the various oils there. The trouble is, I think most of them are biased to the "thin" end of acceptable when new.

As far as specific tests go, you could ask that a compression test and a leakdown test be done to prove that the piston rings aren't damaged. This is a relatively easy test to do on an inline 4 cylinder engine, but it involves removing the spark plugs so it does take some time to do. You can also ask that an injector leakdown test be done to verify that an injector is not slowly leaking fuel into a cylinder. This is slightly more involved, but again, it is not difficult. If it passes those, the problem is going to be more difficult to find - on other cars (Honda) there was a fault in the ECU logic that injected too much fuel under certain conditions.
 
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sm1ke

Work In Progress..
Moderator
Contributor
L
Canada
V
'18 CX-9 Signature
You will either have to go to a different dealer or call Mazda corporate and talk to someone there. If the service manager, whose job relies upon knowing what is acceptable, can't be bothered to determine what Mazda's specs for viscosity are I don't have much faith that things are going to progress at that dealer.

Somewhere in the owners manual will be a phone number to contact a regional manager. Start there. You need to be polite and state that you are concerned about the engine in light of the multiple oil analyses showing fuel dilution. Hopefully, they will give you a case number and contact the dealer so the information can be forwarded up the chain. I'd ask the regional manager the questions the dealer asked you: What is Mazda's position on acceptable fuel dilution and viscosity degradation?

New 5w30 oil should have a viscosity above ~9.2 at a minimum at 100C (and less than about 12.5). You could try to find 5w30 oil with a relatively high starting viscosity to buy yourself a little more time. I haven't been on "Bob is the Oil Guy" forums in many years, but I know I've seen data on the viscosity of the various oils there. The trouble is, I think most of them are biased to the "thin" end of acceptable when new.

As far as specific tests go, you could ask that a compression test and a leakdown test be done to prove that the piston rings aren't damaged. This is a relatively easy test to do on an inline 4 cylinder engine, but it involves removing the spark plugs so it does take some time to do. You can also ask that an injector leakdown test be done to verify that an injector is not slowly leaking fuel into a cylinder. This is slightly more involved, but again, it is not difficult. If it passes those, the problem is going to be more difficult to find - on other cars (Honda) there was a fault in the ECU logic that injected too much fuel under certain conditions.
Just to add to some already excellent advice - when stating your concern about the engine regarding the oil dilution, you can reference the oil dilution issues many Honda CR-V owners are experiencing, leading them to have to change their oil much more frequently than what is specified in the manual. Most people will sympathize with your concern and be more likely to take it seriously. Plus, you might provide some incentive to the Mazda dealer or Mazda corporate by way of giving Mazda the opportunity to show Honda up in terms of customer care.
 

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