2.5 Turbo - Oil Fuel Dilution Issues?

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2010 CX-9 GT
This only applies to GDI (Gas Direct Injection) engines of which Mazda's are not GDI.



Straight from Mazda's website: "Fuel system: Advanced Direct Injection"

It's a direct injection engine. You don't get 310 pound-feet of torque at 2000 rpm any other way.
 
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Mazda CX-9 Grand Touring 2016
The viscosity is out of spec. The viscosity at 100C for 30 wt should be 9.3 to 12.49 centistokes. Your test showed 8.4 cst. Your Pennz started at 10.3 according to their data sheet. That loss could be from shearing, or it could be from gasoline dilution. Do let us know when the lab responds to your question. The silicon at 21 ppm could be either silane anti-foam additive in the oil or dust that passed through the air filter. The wear metals are nice & low. Shell (Pennz) uses moly in the oil for anti-wear. Castrol uses a titanium compound to do the same job. You'll see the difference if you get an analysis with Castrol. The zinc phosphate compound in the oil is anti-oxidant and anti-wear but leaves a high friction layer on the metal. The addition of either the Molybdenum dialkyldithiocarbamate or (cheaper) similar oil-soluble titanium compound provides a low friction hard antiwear layer.
 

sm1ke

Work In Progress..
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Canada
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'18 CX-9 Signature
The viscosity is out of spec. The viscosity at 100C for 30 wt should be 9.3 to 12.49 centistokes. Your test showed 8.4 cst. Your Pennz started at 10.3 according to their data sheet. That loss could be from shearing, or it could be from gasoline dilution. Do let us know when the lab responds to your question. The silicon at 21 ppm could be either silane anti-foam additive in the oil or dust that passed through the air filter. The wear metals are nice & low. Shell (Pennz) uses moly in the oil for anti-wear. Castrol uses a titanium compound to do the same job. You'll see the difference if you get an analysis with Castrol. The zinc phosphate compound in the oil is anti-oxidant and anti-wear but leaves a high friction layer on the metal. The addition of either the Molybdenum dialkyldithiocarbamate or (cheaper) similar oil-soluble titanium compound provides a low friction hard antiwear layer.

Thanks for the explanation, PTguy. You must have some background in oil analysis, or you must also be a member on BITOG.

The rep finally got back to me. These are his words: "Fuel will only be run if the viscosity is low and flagged. If your viscosity is normal, then the fuel won*t be run. I hope this answers your question."

Sounds a little lazy, and he didn't mention how low the viscosity would need to be to be flagged. Does lower cSt = more viscous? If so, I guess the viscosity wasn't low enough for them to run the sample for oil dilution. That may be their general practice but it doesn't really sit well with me, so I'm going to try Oil Analyzers (also in Edmonton) next time.

I usually do an oil change in March/April and another in October/November. I think I'll send the October/November sample out for a UOA since it will reflect the more aggressive driving I do in the summer months.
 
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CX-9 GT 2019
Heh, I did a trip to another dealer and that experience was like from another world. I never thought you can get that much of variation between two same brand dealers 20 miles from each other. Seems like the first dealership does not have anyone proficient enough to do anything other than simple part or fluid change.

This time they took the car for testing once they heard oil level was raising and oil had a gas smell. No stupid questions.

They did tests and confirmed that one injector was leaking. Replaced all injectors.

Easy.

Lets see how the next analysis would look like.
 
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Mazda CX-9 Grand Touring 2016
Does lower cSt = more viscous?
Other way round.The kinematic viscosity test, measured in centiStokes, is by pouring a specified volume of oil, at the specified temperature, through a specific orifice and timing it. The thinner the oil, the faster it flows.
https://www.machinerylubrication.com/Read/411/oil-viscosity

By the way the labeled viscosity grades, called weights, are established in the SAE J300 tables. It gives several specs each viscosity grade must meet including different types of viscosity measures. Any viscosity grade with a W is winter--it doesn't have a hot spec. For example SAE 20 and SAE 20W aren't the same thing. An engine oil that is labeled, say, 5W-30 meets a group of cold specs to be 5W and a group of hot specs to be 30. And...any viscosity grade of 70 or above indicates automotive gear oil. The higher gear oil number doesn't mean it's thicker than engine oil. SAE 40 engine oil is about as viscous as SAE 90 gear oil.
https://www.tribology-abc.com/abc/viscosity.htm#SAE

One of the viscosity tests is the HSHT high shear high temperature test at 150C. It is measured in a different sort of viscometer with a read out in milliPascals. Higher is more viscous. HSHT viscosity relates to both engine wear and oil drag within the engine. Lower wear will result with higher HSHT, but the increased drag results in lower gas mileage. That's a balancing act the oil chemists do when they create one of the energy conserving oils. In any case, the products they sell us all perform very well. (One Pascal equals one Newton per square meter. I don't understand that, either.)
 
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Mazda CX-9 Grand Touring 2016
crimeariver, good going. You knew you had a problem and got it fixed. At the dealership service desk you're pretty much stuck with the service writer and what they (think) they know. Some are sharp, some are willing to explore a problem, and some aren't. I wonder if you'd have better luck at the first one if you'd asked to discuss the problem with the service manager rather than just a service writer. Anyway, the 2nd place has earned your future business.
 
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CX-9 GT 2019
One more point on labs. The Blackstone is very popular lab, but they don't do proper fuel dilution analysis even though they provide the "Fuel %" value in the report.
They simply derive it out of flashpoint test. Their staff seem to think its a reliable test. I have send my previous sample with 3.8% to them in parallel and their recommendation was totally misleading:
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CX-9 GT 2019
Missed this thread? So my issue is back. It took some time to validate due to COVID apparently...

After the "leaky injector change" oil smelled ok after first 1k. After that I did not check much. Got another issue with engine harness and had to tow it for repair.

At 3600k on oil I send it to UOA aaaand...Same 5+%

cx9_oil.jpg


Changed oil and after 2k it smells gas as before.

What makes things worse - that nice dealership that helped me out couple times now trying to avoid taking the car :) They took analysis and said they will follow up with Mazda.

Are those injectors that bad so I got another bad one? Or they simply changed one bad injector, not all as they told. Anyways, if injector is at fault it should be more common.

It would be great if folks here check if oil in their cx9 at least smells.
 
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sm1ke

Work In Progress..
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Canada
:
'18 CX-9 Signature
I recently changed the oil in my 2018 at 43500 km (just over 27000 mi). I didn't smell anything out of the ordinary. My first oil analysis at 29k showed no oil dilution.

I do plan to do another analysis at my next oil change around 50k. I'll be using Oil Analyzers Inc. in Edmonton this time (previous UOA was done by Bureau Veritas, also in Edmonton).
 
I made a recent purchase on a used 2018 CX-9 with 34000 mi. on it. It has almost 36000 mi now and I've noticed the oil levels are above the max line the last 2 times I checked. I'm not sure if I smell gas in the oil. Maybe? My smell ability isn't great, so I tried to compare the smell of the oil to my wife's Prius and it smelled the same to me. Also, i haven't seen a massive color shift either in the oil. Just ordered my OilAnalyzers kit and will report back to y'all ASAP.
 
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Mazda CX-9 Grand Touring 2016
Lim, was the oil--at the same temperature--above the line to start? It's no problem to be a bit high; it is a problem if the level rises due to gasoline or antifreeze entering the system.
 
No, I checked at different temperatures. Once after the engine had been driven, then parked at home to check about 15 minutes later. The other time was cold engine in the morning. Both times the engine oil was above max line.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
No, I checked at different temperatures. Once after the engine had been driven, then parked at home to check about 15 minutes later. The other time was cold engine in the morning. Both times the engine oil was above max line.
If the previous oil change was made by a Mazda dealer, overfill is a norm.
 
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19 Diesel CX-5
Got an analysis for my 2.5T from oil analyzers... aaaand 5% fuel in 3350 miles.. ouch! (nailbyt)
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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.

At the same time got a report for a q5 with 70+k miles. Only 1.6% over 9500 miles. Most of the mileage was rough due to carbon buildup.
Did you ever figure anything out on your fuel dilution issue? I have a 2016 cx9 doinG the same thing.
 
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CX-9 GT 2019
Did you ever figure anything out on your fuel dilution issue? I have a 2016 cx9 doinG the same thing.
Nope. I gave up since the good dealership nearby started to ignore me. Others are further away and I did not bother. Now I'm guessing, they might be dealing with people that require engine replacements... so it's unlikely they have enough loaners for a guy with some harmless oil dilution :)

So I decided to mitigate the issue and live with it if no other red flags.

1. Now I do 2500 oil intervals using cheaper oil. really just use Costco synthetics. And changing oil filter every other time. Since I do the oil change simply because it got diluted - I can save on a mess and environment a bit by leaving the filter :)

2. Make sure I get accurate dilution value. There is one trick to Oil Analyzers. On other forums, I learned that they don't always run the advanced dilution test. Unless you specifically ask in sample notes, they might run a simple test that normally just shows 5% instead of like 3.8-4% or 0% instead of a small dilution. The difference is important because 5% is a max dilution they can detect. If you get that, it could be anything above. Viscosity value is usually a good secondary indicator, though.

So I asked for a detailed analysis, Oil Analyzers ack'ed my request in analysis notes, and the result was 4%.

However, with the recent thread on antifreeze leaks and engine replacements, and in general turned out unresolved issues just bugs me - I'm thinking of trading this one in for a '21 model later this year. I just like it so much :) But hesitant if I should wait for the next-gen model.
 
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19 Diesel CX-5
Thank you for your reply! This info may be irrelevant, but just thought I’d share. I bought this car not too long ago. The engine was replaced under warranty by Mazda(this was PO) I’m the first owner of this new engine. I asked about what caused the failure and they said a “leak” I just assume it was the same that has been popping up. Anyhow my last oil sample test showed fuel dilution and just took another sample and sent it off. 3100 miles on the oil and I can tell just looking at it it’s diluted.
Thanks for the tip about asking for the detailed dilution test. Will do!
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Nope. I gave up since the good dealership nearby started to ignore me. Others are further away and I did not bother. Now I'm guessing, they might be dealing with people that require engine replacements... so it's unlikely they have enough loaners for a guy with some harmless oil dilution :)
Have you tried to take the fuel dilution issue directly to Mazda North American Operations?

So I decided to mitigate the issue and live with it if no other red flags.
That’s unfortunate. But I understand your feelings as I had similar experience with my 2001.5 VW Passat GLX 2.8L V6 5-speed manual when it’s having severe oil consumption issue (1 quart per 800 ~ 1000 miles) since new. It was frustrating it couldn’t get resolved under warranty when the issue is indeed there.

1. Now I do 2500 oil intervals using cheaper oil. really just use Costco synthetics. And changing oil filter every other time. Since I do the oil change simply because it got diluted - I can save on a mess and environment a bit by leaving the filter :)
Apparently Kirkland 5W-30 GF-6 (claimed on the bottle) oil couldn’t help the fuel dilution issue?

Reusing the oil filter does help the environment. BTW, it’s been discussed a while ago, that 50% used oil collected for “recycling” actually got burned off shore. So if you really want to save the environment, use the oil to its maximum serviceable life to reduce the frequency of the oil change. That’s why there’s the “Flexible” oil change interval. And it’s been used in Europe and Asia for many years. Changing oil at 10,000 ~ 12,500 miles based on Flexible OCI notification is a norm there. My 2000 BMW 528i has up to 17,500-mile Flexible OCI!

Mazda should switch to cartridge type oil filter without metal canister which also helps the environment too. Euro engines have been using it for many years (like my 2000 BMW 2.8L I6). Toyota also has switched to cartridge type oil filter on its newer Dynamic Force 2.5L I4.

2. Make sure I get accurate dilution value. There is one trick to Oil Analyzers. On other forums, I learned that they don't always run the advanced dilution test. Unless you specifically ask in sample notes, they might run a simple test that normally just shows 5% instead of like 3.8-4% or 0% instead of a small dilution. The difference is important because 5% is a max dilution they can detect. If you get that, it could be anything above. Viscosity value is usually a good secondary indicator, though.

So I asked for a detailed analysis, Oil Analyzers ack'ed my request in analysis notes, and the result was 4%.
Good to know.

However, with the recent thread on antifreeze leaks and engine replacements, and in general turned out unresolved issues just bugs me - I'm thinking of trading this one in for a '21 model later this year. I just like it so much :) But hesitant if I should wait for the next-gen model.
I’d avoided any similar designed engines. As matter of fact, I gave up the VW entirely after the oil consumption issue on my 2001.5 VW Passat even though I’d been buying new VW’s for many years, no longer a loyal VW customer.
 
Hi, this is my first post here. I have 2019 CX-9 Touring Premium 2.5T AWD that we purchased brand new and now has a little over 5000 miles. It was used very little due to work from home situation etc. I have an appointment this coming Saturday for the 5k service and I was doing a check on the vehicle to see if anything needs to be addressed by the dealer. I pulled the dipstick out and got a very strong smell of gasoline, cleaned it and tried again 3 times and still the same, oil level is well above the hot mark. Hopefully this is a fixable situation, I otherwise love the car.