2013~2016 Oil consumption and poor MPG

2014 cx-5 2.5l fwd 107k miles. Within the last 5 months or so, the gas mileage on my cx-5 has been dropping. Was consistently at 29mpg for over a year but now it's down below 28 and continues to drop. Also within that same time frame, it has started consuming oil. Not sure exactly how much, but dealership said it was "extremely low" several weeks ago. I had been changing the oil myself every 5k miles and it was never low. Dealership changed the oil and replaced #1 ignition coil. I replaced all the spark plugs soon after. MPG is continuing to drop. My first thought was a bad PCV valve but I checked it per Mazda instructions and it passed. What else could be causing these symptoms? Or could the PCV valve still be bad even though it passed?
 
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2018 CX-5 Sport
2014 cx-5 2.5l fwd 107k miles. Within the last 5 months or so, the gas mileage on my cx-5 has been dropping. Was consistently at 29mpg for over a year but now it's down below 28 and continues to drop. Also within that same time frame, it has started consuming oil. Not sure exactly how much, but dealership said it was "extremely low" several weeks ago. I had been changing the oil myself every 5k miles and it was never low. Dealership changed the oil and replaced #1 ignition coil. I replaced all the spark plugs soon after. MPG is continuing to drop. My first thought was a bad PCV valve but I checked it per Mazda instructions and it passed. What else could be causing these symptoms? Or could the PCV valve still be bad even though it passed?

It could be a number of things and we can only guess. Maybe the intake valves have a build up of carbon. Maybe your brakes are dragging. Maybe the gas you bought isn't giving the energy per unit. Or maybe you have been driving in city traffic more. Idk.
 
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2014 CX 5 Touring AWD Bose and Tech
I have the same issue. Mine is at 124k and I'm down to about 26.5 to 27 mpg. I did have a rear caliper go bad and drag which surly hurt my mileage. That said I'm not unhappy with that kinda mpg on a 124k mile vehicle. The caliper dying I attribute to upstate NY winters and our insane reliance on salt spreading.
 

madar

Contributor
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2016.5 CX 5 Touring AWD, 2015 SCION XB
Do a compression test or maybe hook a vacuum gauge to the manifold somewhere. Using more oil and bad gas mileage could be worn rings. Your mileage is getting up there.
 
I'm using the same gas I've always used and have the same driving conditions. I didn't think the skyactiv engines were prone to carbon build up on the valves?

Rings can be worn out after 107k miles? Seems too soon to me.
 

madar

Contributor
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2016.5 CX 5 Touring AWD, 2015 SCION XB
Compression test or vacuum test will tell you the condition of the engine. Making sure nothing mechanically is wrong first would probably be cheaper than to just start replacing parts. You're burning more oil than usual, gas mileage is dropping, you claim the PCV is working...I'd do these quick tests and go from there. I think anything is fair game after 100K.
 
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NelsonLewis

Banned
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16.5 CX-5 GT AWD w/Tech BRMica
Need to define *extremely low* for oil. Also, oil consumption is normal. If we*re talking a quart or less, there may be a problem, but it*s still considered normal...

Run, the dealer isn*t gonna do anything but rob your pockets on this one...
 

madar

Contributor
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2016.5 CX 5 Touring AWD, 2015 SCION XB
Need to define *extremely low* for oil. Also, oil consumption is normal. If we*re talking a quart or less, there may be a problem, but it*s still considered normal...

Run, the dealer isn*t gonna do anything but rob your pockets on this one...

Yeah, I missed that. Is it low because the dealer said it was low or because it's something you've personally been noticing drop faster than usual over the past few months?
 
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GA prior 16 CX5 GT
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20 CX5 GT + Prem
You may have changed to tires that have a higher roll energy requirement. How is your tire pressure? Commute changed to higher speed? Check your oil level more often so you know what is going on...
 
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2013 Mazda CX-5 Sport FWD Auto
Trade it in? That's a bit extreme in my opinion. The drop in gas mileage isn't even that severe.

Could be numerous things as others have suggested. Dirty air filter, wheels out of alignment, less efficient tire brand, carbon buildup in the intake manifold, dirty injectors, failing sensor, etc. I'd try a few things before spending tens of thousands on a new car but that's just me.

I'd investigate the supposed oil consumption a little more as well. Monitor more closely. If you're burning more oil, switch it up to a high mileage formula or go to 5W-30 to see if that slows things down.
 
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madar

Contributor
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2016.5 CX 5 Touring AWD, 2015 SCION XB
Actually, that was my first thought...100K? Problems? Boom, you're gone...
 

shadonoz

SkyActiv Member
Contributor
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State of Jefferson
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2017 CX-5 GT AWD+
Actually, that was my first thought...100K? Problems? Boom, you're gone...

I did it to my last one at 80k. Got rid of it while it still had decent value and avoided the problems.
 

NelsonLewis

Banned
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16.5 CX-5 GT AWD w/Tech BRMica
I did it to my last one at 80k. Got rid of it while it still had decent value and avoided the problems.

Non problematic so far, and it*s already tempting now. Don*t know if this one makes it to 80k. I*d like a little value too...lol
 
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2013 Mazda CX-5 Sport FWD Auto
This group tends to be a bit trade happy. Its not a bad thing, it comes with this niche. Figured Id throw my 2 cents in for feeling the issue out further before throwing in the towel over a loss of ~2 mpg. My CX5 is my daily driver along with my Odyssey, and I couldnt afford to trade my CX5 in just because its approaching 100k, lol. When it approaches 10 years of age, sure, Im shopping to keep things fresh but Im not there yet.
 

NelsonLewis

Banned
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16.5 CX-5 GT AWD w/Tech BRMica
Yea, I*m trade happy, I just have two 15+ year old autos in the stable, one since new. Sure, I wouldn*t mind replacing one of them, but it*s reliable as all get out, and I*d most likely just be trading for trouble...(rolleyes)

I also have been screaming for a Turbo CX-5 since forever ever, and I still ain*t trading, even with the best price in hand on this site by far...

Bye b****, she gone...
 
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alexeyga

Member
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CX-5 2016.5
2014 cx-5 2.5l fwd 107k miles. Within the last 5 months or so, the gas mileage on my cx-5 has been dropping. Was consistently at 29mpg for over a year but now it's down below 28 and continues to drop. Also within that same time frame, it has started consuming oil. Not sure exactly how much, but dealership said it was "extremely low" several weeks ago. I had been changing the oil myself every 5k miles and it was never low. Dealership changed the oil and replaced #1 ignition coil. I replaced all the spark plugs soon after. MPG is continuing to drop. My first thought was a bad PCV valve but I checked it per Mazda instructions and it passed. What else could be causing these symptoms? Or could the PCV valve still be bad even though it passed?

1)Carbon buildup on intake valves
2)Timing chain stretch
3)Carbon buildup on injectors

Ouf if 3, the easiest one to address is #3. If that doesn't change anything and you'll be looking into #1 - might just as well stretch over and do #2 at the same time.
 

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