Transmission fluid change without filter replacement

[PatrickGSR94]

Just had a thought: if people are checking it when the blue light goes off, then the ATF is still much colder than spec for checking, and perhaps that's why people are thinking that Mazda underfills the ATF from the factory? Because it should read lower when it's cold, right?

 

[edmaz]

Just had a thought: if people are checking it when the blue light goes off, then the ATF is still much colder than spec for checking, and perhaps that's why people are thinking that Mazda underfills the ATF from the factory? Because it should read lower when it's cold, right?

Yes, I believe that's definitely correct. And I've also observed readings similar to the ones in your prior post. I'll also add that, after watching the readings on multiple days, the difference between coolant and ATF temps varies quite a bit, depending both on ambient temp, and also if the start was completely cold or the vehicle had been running some number of hours previously.

IMO if owners are checking ATF level when the blue light goes off, or the OBD coolant temp is at 122F, then they are overfilling the fluid if they fill to the upper mark. And, as I've posted previously, I believe that Mazda (or any other automaker) does not send vehicles from the factory with any fluid impactfully underfilled (or overfilled), except for very, very rare mistakes.

Others here have disagreed with this in the past, and may very well do so again. Of course everyone is allowed to have their own opinion, and I'm not going to argue with anyone about it. JMHO, FWIW.

 

[PatrickGSR94]

So I managed to drain ~3.2 to 3.25 quarts out. I put 3.5 qts new fluid in, then started the car and waited for ATF temp to reach 122 again. Checked the level and it looked a bit low this time, so I added about 4 more ounces of fluid. Since I plan to drain and refill 2 more times, I don’t think it’s critical to get it to the exact level.

I did forget to move the shifter through the gears during this process. I need to run to the store in a minute so that will serve to get the gearbox shifting through all gears.

I also got a sample to send to Blackstone, and I will be draining and filling again after a couple of weeks or so.

Is it okay to leave the under tray off during this time so I don’t have to remove it all the next 2 times? I know on Miatas that the under tray splash shield can affect air flow through the radiator.

 

[concept]

I doubt that it would make a huge difference unless you are climbing a mountain at high speed during the Summer. Just keep an eye on your coolant temps.

By the way, oils in general take much longer to warm up compared to engine coolant. When I had my 2001 Corvette, I would leave the digital display in the dash set to oil temperature and I could clearly see that it tool a while longer to get up to operating temps compared to the coolant.

 

[yrwei52]

well I'm embarrassed to say that I'm just now getting around to doing this, despite purchasing 12 quarts of ATF FZ back in March 2019 when the car only had ~84K miles. Life got in the way, I bought a NB1 Miata in July 2019, and that car has had several projects since then. Now the CX-5 is just about to hit 113K miles.

So now it's underway as I type this. I just let the car warm up to verify the fluid level. Used an Autel BT OBD2 dongle, and its app on my phone, and checked it when the ATF temp reported 122 deg.

Something to note, when the engine coolant temp was above 130 (blue light off), the ATF temp was still in the 80's F!! It took at least 10 more minutes of idling to get the ATF up to 122, and at that point the engine coolant temp was in the 150's. So you cannot go by the blue light on the dash. It's not even close.

After the ATF got to 122, I checked the dipstick, and it was just a hair above the lower line. We'll see how much I get to drain out. Also I will be getting a Blackstone fluid analysis of the fluid that comes out of the initial drain.

I was wondering what happened to your ATF change since you mentioned it a while ago.

And when you say “it was just a hair above the lower line”, what is the “lower line” on the ATF dipstick? There’s no “lower line” on the dipstick, only the “marker”. If your factory ATF level is lower than the “marker” at 122°F, your factory ATF is under-filled.

 

[yrwei52]

Just had a thought: if people are checking it when the blue light goes off, then the ATF is still much colder than spec for checking, and perhaps that's why people are thinking that Mazda underfills the ATF from the factory? Because it should read lower when it's cold, right?

You just answered your question by yourself. You drained 3.2 ~ 3.25 quarts of factory ATF, but you have to put back 3.5 quarts + 4 fl oz without shifting gears which may need even more ATF after that. Your factory ATF is under-filled at least 0.375 quarts.

So I managed to drain ~3.2 to 3.25 quarts out. I put 3.5 qts new fluid in, then started the car and waited for ATF temp to reach 122 again. Checked the level and it looked a bit low this time, so I added about 4 more ounces of fluid. Since I plan to drain and refill 2 more times, I don’t think it’s critical to get it to the exact level.

I did forget to move the shifter through the gears during this process. I need to run to the store in a minute so that will serve to get the gearbox shifting through all gears.

 

[yrwei52]

⋯ Is it okay to leave the under tray off during this time so I don’t have to remove it all the next 2 times? I know on Miatas that the under tray splash shield can affect air flow through the radiator.

Like concept said, you should be fine without belly pan installed. I would leave it off when I do multiple ATF drain-and-fills.

Do you plan to replace the ATF filter cartridge? If you do, may be you should do it at the second ATF drain-and-fill like Digbicks1234 suggested in another thread to prevent the accidental leakage issue with new pan sealant. And how did you handle the air box so that you can leave the engine idling and have the space to take the ATF measurement?

2016.5 CX-5 Transmission fluid change questions

 

[yrwei52]

⋯ IMO if owners are checking ATF level when the blue light goes off, or the OBD coolant temp is at 122F, then they are overfilling the fluid if they fill to the upper mark. And, as I've posted previously, I believe that Mazda (or any other automaker) does not send vehicles from the factory with any fluid impactfully underfilled (or overfilled), except for very, very rare mistakes.

Just want to say there’re quite a few people checked the ATF level at 122°F ATF temperature from OBDII reader and found the ATF level was under-filled from factory. Some people are confused with the “marker” on the ATF dipstick and there’s no High and Low lines, only the square “central marker”. Anything measured below the square “central marker” means the ATF level is low. Here’s Kedis82ZE8’s post using OBDLink MX+ and his factory ATF level was low too:

Transmission fluid change without filter replacement

 

[MyFirstMazda]

I haven't checked my level yet because of the placement of the dip stick. The fluid should be hot enough after driving for 20 minutes or so right? Back in the day we just pulled out the dip stick after a drive and checked it as easy as checking the oil level.

 

[ruthrj]

I haven't checked my level yet because of the placement of the dip stick. The fluid should be hot enough after driving for 20 minutes or so right? Back in the day we just pulled out the dip stick after a drive and checked it as easy as checking the oil level.

It might be too hot by then.

 

[erhayes]

I think you can do a drain & refill at any mileage but, NOT a fluid flush. Ed

 

[PatrickGSR94]

Like concept said, you should be fine without belly pan installed. I would leave it off when I do multiple ATF drain-and-fills.

Do you plan to replace the ATF filter cartridge? If you do, may be you should do it at the second ATF drain-and-fill like Digbicks1234 suggested in another thread to prevent the accidental leakage issue with new pan sealant. And how did you handle the air box so that you can leave the engine idling and have the space to take the ATF measurement?

2016.5 CX-5 Transmission fluid change questions

I had not planned on replacing the filter cartridge. Do you think I should? I really didn't want to mess with dropping the pan, especially with how long the car has to sit to let it fully drain and then to let the RTV cure completely. My wife can't drive any of my other vehicles (manual gearboxes on the other cars).

It might be too hot by then.

Definitely too hot. The ATF temp was up to 122 after about maybe 10-15 minutes of idling.

 

[ruthrj]

I had not planned on replacing the filter cartridge. Do you think I should? I really didn't want to mess with dropping the pan, especially with how long the car has to sit to let it fully drain and then to let the RTV cure completely. My wife can't drive any of my other vehicles (manual gearboxes on the other cars).

I’d leave it alone if you don’t want to mess with it. I’m on the fence myself about doing that at 100k. It sounds like a real PITA. I want to drop the pan to clean it off and remove any sludge from the magnet but that may just be OCD.

 

[PatrickGSR94]

I’d leave it alone if you don’t want to mess with it. I’m on the fence myself about doing that at 100k. It sounds like a real PITA. I want to drop the pan to clean it off and remove any sludge from the magnet but that may just be OCD.

Right. I think I'll wait and see how the fluid analysis comes back before I decide what to do next. I remember dropping the pan and changing the filter on my wife's old 96 Corolla with 4-speed slushbox. But of course that was a lot less sophisticated than the Skyactiv 6AT. And it used an actual gasket on the pan.

 

[yrwei52]

I had not planned on replacing the filter cartridge. Do you think I should? I really didn't want to mess with dropping the pan, especially with how long the car has to sit to let it fully drain and then to let the RTV cure completely. My wife can't drive any of my other vehicles (manual gearboxes on the other cars).

If you see how much gunk accumulated to the magnet inside of the ATF pan, you’d have the urge to take the pan down and clean it up, and change the ATF filter cartridge at the same time.

2016.5 CX-5 Transmission fluid change questions

 

[ruthrj]

Oh! That reminds me. If I end up removing the pan I read a cool tip to help reinstall it. Stick dowel rods in the bolt holes of the transmission body. Use those as guides for the pan so you can mate it perfectly to the transmission. Remove the dowel rods as you go to install bolts. Blew my mind how simple that was.

 

[murky]

I'd be more worried about causing a problem where there was none before, in removing and replacing the pan. That seems like a bigger risk than just leaving the original filter in place.

 

[ruthrj]

I'd be more worried about causing a problem where there was none before, in removing and replacing the pan. That seems like a bigger risk than just leaving the original filter in place.

That’s what the competing voice is in my head too lol. If it ain’t broke...

I’m likely going to do it anyway but definitely at my own risk

 

[murky]

That’s what the competing voice is in my head too lol. If it ain’t broke...

I’m likely going to do it anyway but definitely at my own risk

If you enjoy it. I did an unnecessary 4-corner brake job over the Christmas break, so who am I to say anything.

 

[PatrickGSR94]

If you see how much gunk accumulated to the magnet inside of the ATF pan, you’d have the urge to take the pan down and clean it up, and change the ATF filter cartridge at the same time.

2016.5 CX-5 Transmission fluid change questions

man I don't know. Seeing how finicky that pan is with getting the sealant just right, I really feel like I don't want to mess with it. Plus, FOURTEEN quarts of fluid??? I only bought 12 with the intent of draining and refilling 3 times.

As for the question about running the car with the airbox off, I removed the top of the air box, the filter, and then removed that entire lower box and resonator. Then I attached the air box lid back to the intake tube and reconnected the MAF sensor. That way the car could run just fine, while I had easy access to the dipstick.

However I did notice after I finished everything that I had a code relating to the intake air temperature, possibly due to running the engine with the airbox lid just hanging out in open air. I simply cleared that code and it's been fine ever since.