2014 Mazda CX-5 2.5L 128k / Mazda 0w-20 6.8k

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Hey all, my wife and I have owned a 2014 Mazda CX-5 2.5L Touring FWD (Skyactiv non-turbo) since Summer 2016, from 54K miles up to the current 132K-ish miles. I've used OEM Mazda Moly 0w-20 oil and OEM Mazda filters, changed every 6K to 8K miles or so. Since 2019 I've also had Blackstone UOA's performed after every oil change. The reports have always come back looking good, except this last one where they say there may be coolant in the oil.

I have done all maintenance on this car since we bought it, and have not seen any oil or coolant leaking anywhere underneath. The oil itself on the dipstick looks fine, and what drained out last time looked fine. I haven't seen any loss of coolant from the reservoir tank. The car itself seems to drive just fine. Still gets 30+ MPG on highway trips, including our last trip to the Smoky Mountains in July, just after the last oil change.

BS suggests checking back in 4K miles. I'm wondering if I should get another lab to take a look at a sample. I just can't believe this car would be having head gasket issues already. The car has been nearly flawless for the 6+ years we've owned it, and we don't plan on getting rid of it anytime soon, if at all possible. What say ye?

Note that the oil it shows I added between drains on the report is mostly from either a top-end oil leak I had awhile back (VC gasket and oil control valve) and also the tendency for the factory oil fill spec to read low on the dipstick.
 

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You trusted them up until this point right? Bad news suddenly breaks that? The rest of the UOA looks fairly similar to past results so it doesn't seem likely it's a mixed up UOA.

I would say it's time for a closer mechanical inspection. Maybe by a trusted shop.
 
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Makes me wonder how much coolant is 162 ppm.

Anything's possible, including lab contamination.

I guess you checked the coolant for oil drops.

My daily beater putted along 50,000 miles on a slightly leaky head gasket before it showed any noticeable symptoms.
 
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Nothing wrong with a 2nd opinion from Wix/Napa, Amsoil, or Baldwin analysis, or any other lab too.

Well maintained with fancy oil/filter means nothing!

Until the issue is verified with a 2nd opinion, or fixed, I would change the oil/filter every 3k miles. Coolant will destroy your engine.

Could be anything... head gasket, oil cooler if equipped with one, even a leaky radiator, crack in head or block, or block head porosity. Research the known issues with the engine family and don't be surprised.

Some engines just have issues. Be glad that you caught it early. Problem now is finding the source and going from there.

I'd also add a bottle of Subaru coolant conditioner. It might reduce some of the leakage and I haven't ever seen it cause problems. You're headed to a major repair soon.

How many times has the coolant been changed? is the thermostat original?
 
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Makes sense to have another lab do a second analysis just to rule out error on blackstones behalf. Makes more sense just do an analysis on new fill after a couple thousand miles to rule out both human error and any possible contamination do to taking and handling of the sample. Or if somehow the sample got mixed up/ switched accidentally at the lab.
Wix is a cheaper option for UOA. They won’t tell you much about fuel contamination but your concern right now is potential coolant leak.
 
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You either have a head gasket issue or it was a lab or sampling. I'd get the next oil change tested at two labs and if they both say coolant contamination and you're sure you have not contaminated the samples yourself, you have to make a decision.
 

PatrickGSR94

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Yeah I'll see about checking the coolant itself for hydrocarbons, and will likely do a compression and leakdown test on the engine itself here soon. I'm at around 3,500 miles now since that last oil change with the UOA I posted above. I'll probably send samples to both BS and Wix just to see what they find.

I have to admit that I've never changed the coolant. I definitely need to. Mazda Skyactiv recommendations with FL-22 coolant is 120,000 miles or 10 years for the first change, then every 60K after that. So I'm not that far past due.

If it turns out to be a head gasket issue, I guess I'll be digging into that. I'm definitely no stranger to pulling cylinder heads. I've already done it twice, once on one of my cars, and once on my wife's previous Corolla before we traded it on this current Mazda.
 

dnewton3

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This isn't a question of bad advice; BS has suggested you run another UOA soon so that it will confirm or deny the presence of coolant in the oil. That's sound advice IMO. Also, you can ask BS to rerun the sample, if they have enough of it left to run another ICP test. It's entirely possible that they made a mistake; they may have accidentally swapped samples.

You can certainly get another UOA done at another lab; that's OK too. But if both the sodium and potassium are up like in this sample, then you need to accept the reality that there's a problem.
 
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Yeah I'll see about checking the coolant itself for hydrocarbons, and will likely do a compression and leakdown test on the engine itself here soon. I'm at around 3,500 miles now since that last oil change with the UOA I posted above. I'll probably send samples to both BS and Wix just to see what they find.

I have to admit that I've never changed the coolant. I definitely need to. Mazda Skyactiv recommendations with FL-22 coolant is 120,000 miles or 10 years for the first change, then every 60K after that. So I'm not that far past due.

If it turns out to be a head gasket issue, I guess I'll be digging into that. I'm definitely no stranger to pulling cylinder heads. I've already done it twice, once on one of my cars, and once on my wife's previous Corolla before we traded it on this current Mazda.
The hydrocarbon test is pretty iffy. There are better ways to diag this issue. PicoScope with pulse sensor, pressurize cooling system and look in the combustion chamber with inspection camera, leakdown test, etc.
 
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BEWARE. My 2014 Mazda 6 with this same motor was running flawlessly through 180k miles. It is now in the shop as we speak awaiting a motor transplant. I found a donor last week.

Last UOA was fantastic. Always meticulous on every fluid and maintenance requirement as we all are on here. Then suddenly at a drive-thru it started ticking then stumbling on the way home. Only through an engine light right before I got home. No temperature lights. Plugged in my OBD scanner to see what's going on and temp was over 230F after cooling for a bit. pulled dipstick and oil cap and of course filled with Cafe late colored oil. Mazda designed a great motor but left a FATAL flaw with no temp gauge in the cluster. Not once did the car show any sign of hitting high temps. Never threw an engine light until it was too late. I check the codes and sure enough it said coolant temp sensor out, but never told me this. Very disappointing at how the catastrophic loss of the engine could have been disappointed. Had a blown head gasket and never knew it. Not sure how it happened honestly.
 
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Mazda skyactiv 2.5's with bad head gaskets and/or cracked heads is not unheard of. Its not super widespread and certainly not an everyday common occurrence, but if you hang out on Mazda forums at all (I have three Mazda's) you will see it from time to time. Seems to affect the Mexico built engines more than the Japanese built.
 
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Mazda skyactiv 2.5's with bad head gaskets and/or cracked heads is not unheard of. Its not super widespread and certainly not an everyday common occurrence, but if you hang out on Mazda forums at all (I have three Mazda's) you will see it from time to time. Seems to affect the Mexico built engines more than the Japanese built.
You are correct, not a common issue with these motors at all. Just a freak incident and bad luck. My frustration is more with the failure of the temperature monitoring system and the flawed design of excluding a temp gauge from the instrument panel. Without a temp gauge, you're only safety net is the high temp light which in my case, did not function at all. Pulled codes from computer and said coolant temp sensor was faulty. I wish it would have thrown an engine code the day this sensor went out so I could have gotten ahead of this. I'd much rather be paying for a head gasket job than a full motor swap right now. I still love Mazda and this motor. Gives super low wear numbers and runs like the day we bought it even at 180k+ miles.
 
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You are correct, not a common issue with these motors at all. Just a freak incident and bad luck. My frustration is more with the failure of the temperature monitoring system and the flawed design of excluding a temp gauge from the instrument panel. Without a temp gauge, you're only safety net is the high temp light which in my case, did not function at all. Pulled codes from computer and said coolant temp sensor was faulty. I wish it would have thrown an engine code the day this sensor went out so I could have gotten ahead of this. I'd much rather be paying for a head gasket job than a full motor swap right now. I still love Mazda and this motor. Gives super low wear numbers and runs like the day we bought it even at 180k+ miles.


Those days are past. The time and cost involved to replace a head gasket including checking the head surface for trueness would be high. Sure a Indy could do it. I’m not even sure they shave heads on modern engines anymore .

It’s faster to swap engines and send the motor back for evaluation and it it passes then do the work and hold it for the next customer.
 

PatrickGSR94

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yeah I know I could swap out an engine way faster than dealing with changing a head gasket. Took me 2 weeks on my Integra and probably a week or so on my wife's old Corolla, including carrying the head back and forth between my house and the machine shop across town. I could likely get an engine swap done in a weekend, assuming I didn't have to deal with extra broken parts and then waiting on replacements.
 
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Those days are past. The time and cost involved to replace a head gasket including checking the head surface for trueness would be high. Sure a Indy could do it. I’m not even sure they shave heads on modern engines anymore .

It’s faster to swap engines and send the motor back for evaluation and it it passes then do the work and hold it for the next customer.
You are absolutely right. Labor hours are about equal when I was looking into it, so you do save on cost of the engine (if you can find a mechanic that would want to do the job, like you said, they don't want to anymore). In my case, about $2k for one with approx 100k miles. But I would have absolutely preferred to keep my original motor that I had maintained since almost new than get a random motor with unknown history and a 90 day warranty (if the option was available). But since I drove the car until it made ugly noises because no lights went off and I had no clue I was over heating or blew a head gasket, it wasn't worth the risk. I'm sure the bearings and other internals took a beating because of it.
 
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You are absolutely right. Labor hours are about equal when I was looking into it, so you do save on cost of the engine (if you can find a mechanic that would want to do the job, like you said, they don't want to anymore). In my case, about $2k for one with approx 100k miles. But I would have absolutely preferred to keep my original motor that I had maintained since almost new than get a random motor with unknown history and a 90 day warranty (if the option was available). But since I drove the car until it made ugly noises because no lights went off and I had no clue I was over heating or blew a head gasket, it wasn't worth the risk. I'm sure the bearings and other internals took a beating because of it.


I hear ya. I would prefer to keep the original motor but there is that chance of the unknown happening down the road.

Same goes for transmissions. They are generally swapped out now. The old transmission gets rebuilt in a controlled facility.
 
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Hey all, my wife and I have owned a 2014 Mazda CX-5 2.5L Touring FWD (Skyactiv non-turbo) since Summer 2016, from 54K miles up to the current 132K-ish miles. I've used OEM Mazda Moly 0w-20 oil and OEM Mazda filters, changed every 6K to 8K miles or so. Since 2019 I've also had Blackstone UOA's performed after every oil change. The reports have always come back looking good, except this last one where they say there may be coolant in the oil.

I have done all maintenance on this car since we bought it, and have not seen any oil or coolant leaking anywhere underneath. The oil itself on the dipstick looks fine, and what drained out last time looked fine. I haven't seen any loss of coolant from the reservoir tank. The car itself seems to drive just fine. Still gets 30+ MPG on highway trips, including our last trip to the Smoky Mountains in July, just after the last oil change.

BS suggests checking back in 4K miles. I'm wondering if I should get another lab to take a look at a sample. I just can't believe this car would be having head gasket issues already. The car has been nearly flawless for the 6+ years we've owned it, and we don't plan on getting rid of it anytime soon, if at all possible. What say ye?

Note that the oil it shows I added between drains on the report is mostly from either a top-end oil leak I had awhile back (VC gasket and oil control valve) and also the tendency for the factory oil fill spec to read low on the dipstick.
Certainly there nothing wrong with getting a second analysis. I for sure would.
You can also ask BS to re check it.
I’d do that and if BS comes back with the same conclusion I’d do a short, maybe 1k miles, and test again at another lab.
That way you don’t have to wonder. Then either way you can move forward according.
 
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