High Mileage CX-5s - report in

108k miles on a 2017 CX5.

Issues:
Cold start misfires/reduced performance.
Water pump worn bearings, was making a loud noise and was close to failure.
Serpentine belt worn/cracked. Tensioner leaking fluid.

Fix:
Carbon cleaning. Runs like new.
Replaced water pump.
New belt and tensioner.

The transmission does shift rough into 5th and sometimes slips on 3rd, but that was the previous owner's fault for not replacing the ATF at all for 100k miles.
Going to keep the ATF as it is, or do some drain and fills to see if it improves? Drain and fill could be risky later in a vehicles life (or so I’ve read), but was curious if you had tried any actions.
 
Going to keep the ATF as it is, or do some drain and fills to see if it improves? Drain and fill could be risky later in a vehicles life (or so I’ve read), but was curious if you had tried any actions.

I have done two drain and fills. The first one improved shifting. The second one made them worse. I figured I won't even try to drop the pan and replace the filter as that would remove even more metal particles in the fluid and affect friction.
 
I wonder where the record holder is now. Must be over 400k. Makes me feel good about mine, considering it's basically the same car except mine's black.
 
I just crossed over the 100k barrier in my 2016.5 CX-5 GT. My wife and I love it and really want to drive it until it won't drive anymore.

I have done all oil changes myself with OEM Moly oil and regular intervals.

Having said that, I unfortunately am just now educating myself on transmission fluid changes (front and back?). It appears that I may have too many miles on the vehicle to do a pan drop and filter change? Knowing I'm darned if I do and darned if I don't is not a great feeling. I saw the idea of doing a half-fluid drain/fill to help extend life. I will keep surfing the thread but please let me know what you would do in my situation!
 
I just crossed over the 100k barrier in my 2016.5 CX-5 GT. My wife and I love it and really want to drive it until it won't drive anymore.

I have done all oil changes myself with OEM Moly oil and regular intervals.

Having said that, I unfortunately am just now educating myself on transmission fluid changes (front and back?). It appears that I may have too many miles on the vehicle to do a pan drop and filter change? Knowing I'm darned if I do and darned if I don't is not a great feeling. I saw the idea of doing a half-fluid drain/fill to help extend life. I will keep surfing the thread but please let me know what you would do in my situation!
At 100K miles I’d still do a drain-and-fill first and see how the transmission behaves. Then do it again the second time if nothing goes wrong. If after several hundred miles of 2 drain-and-fills you have no issues on the transmission, then you can try drop the pan and replace the filter cartridge inside. Of course you always have some risk when you change the ATF at 100K miles, but I believe this’s a risk to take if you still want to keep your 2016.5 CX-5 for another 100K miles. Make sure to use Mazda OEM ATF FZ for the AFT change.

There’re other services coming up at your CX-5’s mileage and age, FL-22 coolant change. And if you have an AWD and haven’t done so, front transfer case and rear differential gear oil (with OEM SG1).
 
I just crossed over the 100k barrier in my 2016.5 CX-5 GT. My wife and I love it and really want to drive it until it won't drive anymore.

I have done all oil changes myself with OEM Moly oil and regular intervals.

Having said that, I unfortunately am just now educating myself on transmission fluid changes (front and back?). It appears that I may have too many miles on the vehicle to do a pan drop and filter change? Knowing I'm darned if I do and darned if I don't is not a great feeling. I saw the idea of doing a half-fluid drain/fill to help extend life. I will keep surfing the thread but please let me know what you would do in my situation!
I did the 3 drain/fill method with a pan drop and filter change on the 3rd drain, at around 112K miles. Wish I had done it sooner, but it definitely wasn't a bad thing to do it when I did. I waited about a week or two between each drain and fill. Used 12 or 13-ish quarts of FZ, new OEM filter, and OEM Mazda sealant (could have used Hondabond or Permatex Ultra Grey also) to reseal the pan. By my calculations it should have around 90% fresh fluid in the whole system after the 3rd drain and fill.
 
@PatrickGSR94 , @yrwei52 Thanks for the awesome suggestions. I think I'll go ahead and do it. Should I try to do front transfer case and rear differential gear oil (with OEM SG1) now, or is there a certain mileage that I'm looking for?

Should I be doing anything with belts?

thanks!
 
@PatrickGSR94 , @yrwei52 Thanks for the awesome suggestions. I think I'll go ahead and do it. Should I try to do front transfer case and rear differential gear oil (with OEM SG1) now, or is there a certain mileage that I'm looking for?

Should I be doing anything with belts?

thanks!
Yes IMO you should go ahead change the gear lube in front transfer case and rear differential now if you have never done so. Make sure to get more than one bottle of SG-1 for both as the rear differential needs 0.7 ~ 0.8 quart instead of 0.48 quart specified in the manual. There’s no specific maintenance schedule by Mazda other than if the AWD vehicle submerged in water; or a 30,000-mile change interval on rear differential in some severe driving conditions.

The serpentine belt tensioner is prone to leak. At 100,000 miles I’d imagine it’s a good time to replace the tensioner even if it hasn’t leaked. You then replace the serpentine belt AND water pump belt at the same time.

You also want to remove the engine top cover and see if the Oil Control Valve Solenoid (PE01-14-420A) is leaking.

Finally, you can consider to use (Mazda recommended) 5W-30 full synthetic oil instead of Mazda Moly 0W-20 oil which should reduce the oil consumption and valve train noise at your mileage.
 
I’ve had such good luck with the Mazda Moly since new…and no noticeable oil consumption at around 78K miles I will likely continue on with it for the foreseeable future. I would only change at this point if consumption issues began to appear.
 
@yrwei52 To be honest dropping the transmission pan makes me a bit nervous. I like servicing my vehicles myself but I have never tried anything quite like that. Is that final step absolutely necessary or would 3 good drain & fills suffice.

Put a different way, if 3 liquid changes + pan cleaning/filter change = 100% benefit, what percentage would I be at forgoing the last bit.

thanks!
 
If you’re doing it yourself and are nervous, I wouldn’t bother. I’m comfortable with the procedure and to be honest I accidentally cross threaded one of the many pan bolts during reinstallation. I noticed when it was screwed in about half way and started feeling more resistance than I should. I just screwed it in the rest of the way (one of the final bolts) and called it a day. The transmission housing is aluminum so that’s one possible way to screw something up.

My filter wasn’t very dirty when I removed it at 100k miles on my CX-5. Cleaning the magnet off was my primary goal and was happy to get that. However, there are plenty of high mileage CX-5 owners here who have never replaced the transmission filter or dropped the pan.
 
@ruthrj That makes me feel better- so it sounds like just doing the drain & fill 2-3 times would still be a very good maintenance idea, along with the other things mentioned. Thank you!
 
I personally would (and did) drop the pan and change the filter also. I had never done it before, and never resealed any type of oil pan with RTV before (I'm used to ones with gaskets). But I used Mazda OEM sealant (it's really the exact same as Permatex Ultra Grey), and got it done no problem. I even bought a few new bolts because a few of mine looked rusty. I also used a good inch-lbs torque wrench to ensure even torque on the bolts all around.

When I did my Miata engine-out resealing project this past winter, which included RTV on several parts including the oil pump and oil pan, I did Permatex Ultra Grey in an acutal caulk tube. Everything went on perfectly, as close to OEM as a human probably can get it. My RTV lines were only slightly more squiggly than when the robots apply them in the factory. :p
 
If you’re doing it yourself and are nervous, I wouldn’t bother. I’m comfortable with the procedure and to be honest I accidentally cross threaded one of the many pan bolts during reinstallation. I noticed when it was screwed in about half way and started feeling more resistance than I should. I just screwed it in the rest of the way (one of the final bolts) and called it a day. The transmission housing is aluminum so that’s one possible way to screw something up.

My filter wasn’t very dirty when I removed it at 100k miles on my CX-5. Cleaning the magnet off was my primary goal and was happy to get that. However, there are plenty of high mileage CX-5 owners here who have never replaced the transmission filter or dropped the pan.
Really, unless you experienced a catastrophic loss of the torque converter or transaxle, which dumped a bunch of debris into the fluid, there is close to zero benefit--other than warm fuzzies-- for changing the filter. In the majority of scenarios, the trans filter is a lifetime part.
 
Really, unless you experienced a catastrophic loss of the torque converter or transaxle, which dumped a bunch of debris into the fluid, there is close to zero benefit--other than warm fuzzies-- for changing the filter. In the majority of scenarios, the trans filter is a lifetime part.
I've wondered about the filter being adequate for many thousands of miles but what about time. For owners who keep the car for 15-20 years, does the filter slowly deteriorate and add to debris in the transmission. I've had mine for 9 years and plan on keeping it for a long time. I would love to not have to change the filter but due to past habits I don't get any warm fuzzies from not changing it.
 
I've wondered about the filter being adequate for many thousands of miles but what about time. For owners who keep the car for 15-20 years, does the filter slowly deteriorate and add to debris in the transmission. I've had mine for 9 years and plan on keeping it for a long time. I would love to not have to change the filter but due to past habits I don't get any warm fuzzies from not changing it.

I changed a trans filter exactly ONE in the last 30 yrs, as I had a slightly leaking pan and was in there anyway. It was an unrewarding experience, as the filter was no where near "clogged".

Also interesting to note that filters which LOOK like they SHOULD be clogged (observable surface debris) will often flow test to 80% (or better) of a new filter.

A university did a controlled test for engine air filter flow a decade ago, on 4 or 5 vehciles, as I recall. They discovered that there was low single digit changes in flow up to the point where the clogging caused a large enough pressure differential to deform (collapse) the filter, where the filter flow substantially dropped.

The only joy I've had with filter changes were cabin filters, which DO get horribly clogged in 30k miles, and can cause an uptick in fan speed for a system to maintain temperature, and generate more noise as the fan attempts to suck air through it. The cabin filter is much more sensitive as the pressure differential is a tiny fraction of that of the engine air filter or any of the fluid filters.
 
@yrwei52 To be honest dropping the transmission pan makes me a bit nervous. I like servicing my vehicles myself but I have never tried anything quite like that. Is that final step absolutely necessary or would 3 good drain & fills suffice.

Put a different way, if 3 liquid changes + pan cleaning/filter change = 100% benefit, what percentage would I be at forgoing the last bit.

thanks!
Changing the filter cartridge inside of the automatic transmission is a good “practice” like changing the engine oil filter. They hardly get “clogged” during the service life. Both sides of opinion are legit, and I myself prefer changing it at certain point. The benefit of dropping the transmission pan is you can change the filter cartridge and clean up the magnetic mentioned above, and one additional benefit is you can drain more used ATF out (about 1 quart or more) if you replace the filter cartridge with a pan drop.

If you aren’t comfortable doing the RTV resealing, you can buy some aftermarket filter cartridge which comes with a rubber pan gasket and it should be a lot easier to reinstall the pan. The only problem to me is we don’t know the proper torque value for the pan bolts if we use a rubber pan gasket. It has to be different from using the RTV. Of course you can just do the drain-and-fill 3 times, which should be still better than not doing any ATF changes at all IMO.

The shop manual does call for new pan bolts but many people just reuse them. You had better clean the aluminum thread for pan bolts throughly to prevent the possible cross threading.
 
Great discussion here! Balanced talk for both sides and I love that. I used new pan bolts so imagine my frustration when I cross threaded one, lol! I must have screwed it in at a wrong able or something. If you reuse the bolts, you’ll definitely want to hit them with a wire brush on a dremel or something. Think that was suggested in this thread. Great way to knock the old RTV off.
 
Great discussion here! Balanced talk for both sides and I love that. I used new pan bolts so imagine my frustration when I cross threaded one, lol! I must have screwed it in at a wrong able or something. If you reuse the bolts, you’ll definitely want to hit them with a wire brush on a dremel or something. Think that was suggested in this thread. Great way to knock the old RTV off.
You hit on a couple of good points here. The wire wheel on my bench grinder cleans up bolt threads nicely. Regarding cross threading, I try to have taps on hand (plug taps since it's the lead-in threads that get knackered) for the sizes and thread pitch of bolts that thread into aluminum like transmission housing, throttle body, alternator etc. Helps to minimize chances of being 'dead in the water'. It seems that Mazda likes the finer thread pitch of 1.25 mm , so I had to add to my tap & die set to encompass M8,M10 and M12 in 1.25mm pitch.
 
common best practice for any bolt hole near RTV is to run a tap or thread chaser through it to ensure no dried RTV is in there, especially important for blind holes. I know the Miata service manual has diagrams specifically warning about this issue. CX5 one probably has something similar.
 

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