ATF...Change or not?

[Conrad 16.5]

I love how people who admit they've only read about the job absolutely, totally, and completely know more about a subject than someone who has actually done it a couple dozen times over several different vehicles over a couple of decades.

I apologize for offering insight gained from actual experience instead of being a forum expert who's only read about it. You're right. You are far better off paying someone $500 to do this, because it's far, far beyond the capabilities of even the most advanced DIY'er.

I am wrong, and really need to heed the old adage: "Tis better to keep your mouth shut and be thought a fool, then open it and remove all doubt."

Wow, you sure are getting your panties in a bunch over this.

You may be right, but...

I've been wrenching on cars and bikes for nearly 50 years, and I've done hundreds of oil changes over those years. I've also done many a transmission drain and fill too.

The ONLY trans drain and fill that was almost as easy an oil change was/is my Silverado with Allison transmission. The trans pan has a drain port, just like the engine oil pan, and it has a spin on/off trans filter.

I've read the procedure for a drain/fill on the CX and, while it doesn't sound difficult, the air box has to be messed with and the fill port on the CX is not as easy to get at as the engine oil port. Also the temp has to be taken into consideration. Additionally, if you're changing out the in-pan filter, that opens another can of worms. Does that sound as easy as an oil change?

If you're talking about/to me above, where did I say anything about paying someone else $500 to do this job?

Saying all that, I appreciate the knowledge you bring and share with us here. I just don't understand why this is such a thing for you.

 

[Kedis82ZE8]

- On ramps easy to remove the covers under the bottom with a cordless tool of your choice.

- You can either remove the dipstick bolt from the bottom or use an extension on a 1/4“ wrench from the top. Then either remove the dipstick bolt from the bottom or one of those magnetic/flexible reach tools they sell at HF from the top.

- These small funnels with long tubes on them that you can snake down to dipstick fill work fine and easy fill from the topside

https://www.amazon.com/dp/ (commissions earned)

OBDLink/OBDFusion/FORScan are good options to use for ATF temp monitoring.

I normally use OBDLink most often

Again… I don’t touch the air box when I change the ATF Fluid in mine.

I also realize not everyone has 4 ramps or wants to work under vehicle like that so personal comfort level has to come into play.

 

[MM8]

Thanks for the detailed report. Were you able to just sway away the whole air filter box with wires connected to check the ATF level with engine running on your 2.5L NA / CD / 2020 CX-5?



Do you mind to tell us what kind of scan tool (type、brand、model) you’re using?



According to 2020 Mazda CX-5 owner’s manual, the ATF capacity on 2.5L NA / CD is 7.8 L / 8.2 US qt OR 8.0 L / 8.5 US qt without any comments. And the 2.5T on the same MY has 8.0 L / 8.5 US qt. The 2.5L NA on my 2016 CX-5 has 7.8 L / 8.2 US qt. Most people reported 1.25 ~ 2 quarts additional ATF are needed for the pan drop with a filter cartridge change.



I noticed that too on the other day. And the price is for 1-liter bottle which is a bit more than US ATF FZ quart bottle. Just hope the shipping from Canada won’t be too expensive.



Many here felt there’re too much metal shavings and gunk on the magnet even on the pan for the first pan drop. Here’s the report from @Digbicks1234 at 63K miles:

2016.5 CX-5 Transmission fluid change questions

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Thanks for reporting your experience.



Most drive a week or two then do the second ATF change. I guess the ATF should be mixed very well between fresh and old once the engine is running and the transmission had been shifted into every gear.

So far I’ve seen people here doing the pan drop the last during 3 drains-and-fills. You’re the first did the pan drop and filter change the first.


Although you said the original filter only held back a cup or so, but the filter element also absorbed plenty of ATF which couldn’t be drained. You should only need about 3.75 quarts to do a simple drain-and-fill, not 5.25 - 0.5 = 4.75 quarts. You may have a transmission with bigger capacity and that’s about 0.3 quart more. Please report back what you found.



I believe the reason why the pan gasket from WIX WL10379 wouldn’t fit is because your transmission is the newer version with 0.3 quart bigger capacity.

Some would want to buy a new pan for less effort on RTV cleaning job. They also need to watch out making sure to get a correct one as the pan shape and screw hole locations could be different due to the capacity change.

I removed the entire airbox. The dipstick /fill hole is not particularly accessible without removing the air box. Fair warning; when you start the car to get the transmission up to temperature, you'll get a charging system warning telling you to shut off the engine, and a half dozen other warning lights. Ignore it, it only takes 15 minutes to get the transmission up to 120 degrees F - 20 minutes total getting to temperature and check and adjust the fluid level. After you've put the airbox and reconnected the MAF sensor wiring, everything goes back to normal, except there is a check engine light. I cleared the codes with my scan tool, and everything is right with the world.

The scan tool I use is a ThinkCar Thinktool ProS - about $1,200 + a $400 annual subscription fee after the first 2 years. I don't mind paying this because even though I'm retired, I still do a lot of automotive repair.
My last scan tool was a Matco Maxme which was much more intuitive. The touch screen went out, Matco dropped the scan tool from their inventory and no repair parts were available - Thanks for the $1,600 paperweight Matco!

The fluid capacity new and dry is 8.5 quarts. The torque converter and transmission cooler don't drain whether it's a drain and fill, or dropping the pan and changing the filter. I reported the amount of fluid that actually drained from the transmission - real world data.
The reason I estimate draining the transmission today will take .5 quarts less on the drain and fill is because the filter held back about a cup of fluid, and the pan did not completely drain, even though the car was completely level when the service was performed.

Mazdashop with shipping was half of the cost from what my local Mazda dealership is charging. Do what I did and buy 10 liters.

It doesn't take a week or two for the new fluid to mix in with the old. I drove it for 45 minutes yesterday, and will drive it long enough to get the fluid hot before I drain it today. That is way more than sufficient to mix the fluids.

Normally when the pan is pulled for the first time to do a transmission service, the magnet looks like a round version of Groucho Marx eyebrows, and the bottom of the pan is lightly covered in finely ground clutch material - think coffee grounds; "a couple three" tablespoons full - this is typical and normal. Mine had a bit less metal on the magnet than the one pictured, little in the way of clutch material. After looking at transmission pans for years, I was pleasantly surprised. The magnet pictured has such a small amount, as to be classified as better than normal.

 

[AVC]

A few thoughts from someone who recently did a drain and fill. I didn't mess around with scan tool, or check when idling, etc.

Modern Group III, Group IV fluids change volume a LOT with temperature. Thus the impetus for a complicated procedure, which I presume is provided to shops who don't want to have their service bay full of overnight vehicles they are waiting to reach ambient temp--the same temp as the new fluid in containers.

My presumption is that whatever the fluid level was from the factory is fine, plus or minus--it shifted perfectly for 60K+ miles, so emperically the fluid level must have been within design range. The fluid level can be +/- 5 or 6 ounces, AT LEAST--no foul.

To avoid the whole trans fluid temp issue, I parked the car on the level garage floor overnight so the fluid being drained is the same temp as the new stuff in the bottle.

Drain the fluid. Measure it--I use an empty 5 gt oil container that has accurate graduations (I measured prior). Any other reasonably accurate graduated container is fine. Pour in new fluid of the same volume +/- a few ounces.

Done.

I do the same on my '20 Pilot that has a similar complicated factory procedure.

 

[yrwei52]

A few thoughts from someone who recently did a drain and fill. I didn't mess around with scan tool, or check when idling, etc.

Modern Group III, Group IV fluids change volume a LOT with temperature. Thus the impetus for a complicated procedure, which I presume is provided to shops who don't want to have their service bay full of overnight vehicles they are waiting to reach ambient temp--the same temp as the new fluid in containers.

My presumption is that whatever the fluid level was from the factory is fine, plus or minus--it shifted perfectly for 60K+ miles, so emperically the fluid level must have been within design range. The fluid level can be +/- 5 or 6 ounces, AT LEAST--no foul.

To avoid the whole trans fluid temp issue, I parked the car on the level garage floor overnight so the fluid being drained is the same temp as the new stuff in the bottle.

Drain the fluid. Measure it--I use an empty 5 gt oil container that has accurate graduations (I measured prior). Any other reasonably accurate graduated container is fine. Pour in new fluid of the same volume +/- a few ounces.

Done.

I do the same on my '20 Pilot that has a similar complicated factory procedure.

The problem to me by pouring the same amount of ATF drained back into the transmission at the same room temperature is it’s been verified many times that the factory fill is low, sometimes even below the Low line on the dipstick, if we follow the proper procedure stated in the workshop manual to check the factory fill.

 

[AVC]

But.....it really doesn't matter. When was the last (believable) posting that someone experienced shifting, durability, implosion or other issues because the factory fill was "wrong"?

The transmission worked perfectly prior, so the factory fill was adequate, and apparently within some fill tolerance Mazda considers acceptable and empirically (by me) to be OK before 60k and now at 70k+, as well.

Just seems like more naval gazing than necessary for a drain and fill.

 

[MM8]

I love how people who admit they've only read about the job absolutely, totally, and completely know more about a subject than someone who has actually done it a couple dozen times over several different vehicles over a couple of decades.

I apologize for offering insight gained from actual experience instead of being a forum expert who's only read about it. You're right. You are far better off paying someone $500 to do this, because it's far, far beyond the capabilities of even the most advanced DIY'er.

I am wrong, and really need to heed the old adage: "Tis better to keep your mouth shut and be thought a fool, then open it and remove all doubt."

I'm a retired tech who worked in a transmission shop for years. I likely serviced more transmissions in 2 weeks than you've done in a lifetime.

I never saw an oil change where the airbox had to be removed to access the dipstick or pour in the new oil. I've never seen an oil change where the oil pan had to be removed, cleaned, re-gasketed, and reinstalled in order to change the oil filter. I never saw an oil change where I had to connect a scan tool to the car to get the perfect temperature range, in order to fill the oil to the correct level. I never saw an oil change which required a 2 foot long funnel with an extremely narrow opening to pour the oil into the engine. With few exceptions, most oil changes don't require the underbelly pan to be completely removed in order to accomplish the job. I've never seen an oil dipstick which was bolted into place. I've never had to unplug a MAF sensor in order to do an oil change.

 

[MM8]

Why would you do maintenance faster than Mazda suggests? i trust Mazda engineers know what they are doing, which is why I bought a Mazda in the first place. I have not read about widespread failures to engines or the power train on Mazda vehicles, is there evidence otherwise? I follow the maintenance schedule in the book, including oil changes at 7500 miles, not 5000 like I read many on this forum do. There is no way Mobil 1 and a Mazda skyactiv engine need more frequent changes.

That said, contrary to the manual, I do believe that differential fluid, transfer case fluid and trans fluid are NOT lifetime fluids and will change them out at some point at or around 60-100k miles.

Engineers write maintenance schedules according to a planned service life.

Corporate executives tell the engineers what they want the service life to be - typically 100,000 miles. Why? The car is well out of warranty, and if the car has no major problem in 100,000 miles, most new car buyers are happy. 7,500 mile oil change intervals, and "maintenance free" transmissions look good to less than knowledgeable consumers, but are done at the detriment of component service life. Back in the 90's cars had just enough tech to be super reliable, and were on old school service schedules. Those cars would go 300,000 and 400,000 miles with proper maintenance. This was all at the detriment of selling new cars.

The car manufacturers aren't going to make that mistake again.

 

[madar]

But.....it really doesn't matter. When was the last (believable) posting that someone experienced shifting, durability, implosion or other issues because the factory fill was "wrong"?

The transmission worked perfectly prior, so the factory fill was adequate, and apparently within some fill tolerance Mazda considers acceptable and empirically (by me) to be OK before 60k and now at 70k+, as well.

Just seems like more naval gazing than necessary for a drain and fill.

yep, as long as it's between the lines on the stick at the prescribed temperature, doesn't natter if it's on the lower end or the upper end, and as long as you're not leaking then you're golden.

 

[AVC]

yep, as long as it's between the lines on the stick at the prescribed temperature, doesn't natter if it's on the lower end or the upper end, and as long as you're not leaking then you're golden.

Well, further to the point, if I added back as much fluid as I drained, and both fluids were at the same temp, then they were the same volume. One could certainly (I didn't) check the fluid level on the stick before draining, and while the trans was at ambient, and then look at the stick again the next day after filling, and the car had been driven, and when the trans was ambient again.

 

[madar]

Unfortunately they have followed what a lot of the industry has moved to and its ~270*f. Over 230* and fluid will start to break down and the static/dynamic coefficient of friction starts to change rapidly.

Used to be years ago a rule of thumb was that for every 20 degrees your transmission goes above 200, its life span is cut in half, or maybe they were talking about fluid. No longer true with newer fluids?

 

[madar]

Well, further to the point, if I added back as much fluid as I drained, and both fluids were at the same temp, then they were the same volume. One could certainly (I didn't) check the fluid level on the stick before draining, and while the trans was at ambient, and then look at the stick again the next day after filling, and the car had been driven, and when the trans was ambient again.

That's exactly how I did it, stone cold. But I checked it with an OBD plug for the "hot" level.

 

[sinistriel@]

Used to be years ago a rule of thumb was that for every 20 degrees your transmission goes above 200, its life span is cut in half, or maybe they were talking about fluid. No longer true with newer fluids?

Heat is the enemy of an automatic. The newer fluids like FZ are very high quality and have a much higher tolerance to heat than older fluids but keeping a transmission around 200* or cooler will pay dividends for component life.

 

[yrwei52]

Well, further to the point, if I added back as much fluid as I drained, and both fluids were at the same temp, then they were the same volume. One could certainly (I didn't) check the fluid level on the stick before draining, and while the trans was at ambient, and then look at the stick again the next day after filling, and the car had been driven, and when the trans was ambient again.

Here’s a recent example that @FerrariF1 originally thought his ATF level from factory was fine with engine stopped on his CX-5 2.5T. Once he rechecked with engine idling, he needed about 600ml (0.635 quart!!!) to bring the ATF level to the Full mark (although the ideal level should be at the middle block area). Mazda under-filled the ATF in his transmission as usual at the factory. That’s why if you re-fill the same amount of fresh ATF as drained, your ATF level most likely will be too low.

He also did an experiment and found the differences on ATF level in different ATF temperatures on his CX-5 with 2.5T:

You guys were right, I checked the ATF while idling and it was low. The ATF was at around 25-30 C (77-86 F). I added 600ml and it came up to the middle of the 2 lines, so perfect. I don't think ATF expansion is that great that I need to check at 122F, and I'm guessing if I were to check at 122F it would be closer to the top line.

I also changed the rear diff and front transfer case, and they both took about 0.5L each. Not too complicated.

Update: I warmed up the transmission fluid to 51C / 123F and re-checked level (car idling, level surface) and it was just below the Full line. MS Paint artwork attached.

Summary: added 600ml to factory fluid to bring it up to full level. I did not drain and fill since car has 30K km / 18K miles.

View attachment 320332

So the question is should we follow the official procedure by Mazda Workshop Manual to bring up the ATF to the proper level, or do we settle for whatever the factory-fill level was which has been proven probably too low during the re-fill?

A similar dilemma is on gear lube level for our real differential. The factory-fill has been proven low by 50% or more. When you change it do you follow Mazda’s capacity spec and put back in 0.48 qt (or 0.37 qt for gen-2 CX-5), or do you follow Mazda Workshop Manual and fill it up to the brim of the filler hole which will need 0.7 ~ 0.75 quart?

I definitely will follow the procedures outlined in Mazda Workshop Manual checking the fluid levels.

 

[theblooms]

I always follow the Owner's Manual or FSM.

 

[yrwei52]

I always follow the Owner's Manual or FSM.

So you always put in 4.4 quarts (stated in owner’s manual) for your (engine) oil change on your 2.0L? That would make your oil level near the Add mark of the dipstick.

And what do you do for your rear differential? The owner’s manual says 0.48 quarts, and the Mazda Workshop Manual says use 0.48 quart to fill to the brim of the fill hole, but you actually need at least 0.7 quart to reach the brim of the fill hole?

 

[theblooms]

So you always put in 4.4 quarts (stated in owner’s manual) for your oil change on your 2.0L? That would make your oil level near the Add mark of the dipstick.

And what do you do for your rear differential? The owner’s manual says 0.48 quarts, and the Mazda Workshop Manual says use 0.48 quart to fill to the brim of the fill hole, but you actually need at least 0.7 quart to reach the brim of the fill hole?

Don't have a rear diff. And I add to the top of the full mark at 149°F idling (or whatever temp the manual says)

 

[FerrariF1]

So you always put in 4.4 quarts (stated in owner’s manual) for your (engine) oil change on your 2.0L? That would make your oil level near the Add mark of the dipstick.

And what do you do for your rear differential? The owner’s manual says 0.48 quarts, and the Mazda Workshop Manual says use 0.48 quart to fill to the brim of the fill hole, but you actually need at least 0.7 quart to reach the brim of the fill hole?

For the rear diff, my 2021 AWD Turbo only took about 0.48 quart (a bit under 0.5L) before fluid was spilling out of the fill plug. Nowhere near 0.7 quart...

 

[yrwei52]

For the rear diff, my 2021 AWD Turbo only took about 0.48 quart (a bit under 0.5L) before fluid was spilling out of the fill plug. Nowhere near 0.7 quart...

Good to know and thanks for the finding! You’re the first one here reported not using 0.7 ~ 0.75 (US) quart to reach the brim of the fill hole. But you also have the newest CX-5 (2021) changing the rear differential gear oil.

Firstly 0.5 liter = 0.528 US liquid quart = 0.44 Imperial quart.

Since most members here are in the US, so when I say quart, I mean US liquid quart. I wish US can switch to metric system (remember we tried in 70’s with km on the highway sign and liter on certain gas station pumps) like every other countries in the world so no more confusions and inconveniences, but I digress.

Based on several TSBs Mazda has redesigned the rear differential front casing several times to fix the problem of premature failure on front input shaft bearing. It could change the capacity along the way, or Mazda eventually relocated the fill hole making it lower on your 2021 CX-5 AWD.

Still, the capacity spec in your 2021 CX-5 owner’s manual says 0.35 L / 0.37 (US) quart for rear differential. Do you prefer putting in 0.35 L or 0.5 L (to the brim of the fill hole) of gear lube in your rear differential for the change? We’re talking about putting in 43% more than Mazda specified quantity here!

 

[moonj]

Just done ATF on my 2017 CX5 yesterday (removed pan- replaced filter---applied RTV again)

Draining for a few hours but only put back about 4.1-4.2L transmission fluid. Is this normal?

Then should I do it again after a while? From the above chart the total amount is like 7.8L- 8L

Also my OBD tool doesn't show the ATF temp, I started the car and running about 10 mins, when I check the level looks fine. So if temp low will the level high or low?