Transmission pan filter change at 159K miles

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2017 CX3 Touring AWD
8/29/25 Oil/filter change at 159K miles
The first fluid drain/fill was at 153K miles. Two more rounds of drain/fill were done before 155K miles. Decided to replace the filter and reseal the pan because there was a leak from the corner seam. What took me the longest was to scrape off the pink RTV residue from the transmission and pan. It was easier on the transmission because the surface is flat. The fluid kept dripping onto my hair and clothes though. The pan, on the other hand, was a pain. Much of the residue stayed with the pan, and the surface has indentation. The cheapo putty knife scraped off the thick part, and a piece of steel wool took care of the rest.

The fluid was all grey. Mostly blue Aisin FZ, with some traces of red Idemitsu Type M and old OEM. Collected a sample to send to the lab for metal contents. There wasn't too much junk at the bottom of the pan. The magnet collected shreddings like baby hair.
 

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Additional pics. Once the 16 bolts came off, I sprayed them with degreaser in a cup and let them soak. Took 3 rounds until the fluid became clear. Then I had to dry them and remove the RTV residue as much as I could. I know the book says use new bolts.

The rubber o-rings in the new filter got lubed with some fresh ATF in a cap. The two bolts securing the filter are longer than the pan bolts.

Old fluid looks brown in my black drain pan, but it is actually grey when dipped in white paper towel.
 

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This picture shows how much of the old fluid remains in the pan while the draining was down to a slow drip. This is quite a bit, maybe half a quart?

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This picture shows the oil pan. No leaks around the seams. The drain valve is at the rear so when I put the front wheels on ramps at home, it helps getting the oil out. Did the 159K oil/filter change a few days ago, only paid $53 for oil and filter. While waiting for the RTV to cure, I rotated the tires and adjusted the pressure. That's $40 saved from going to the tire shop. Will wait until the end to torque-tighten the lug nuts.

In half an hour I will fill the transmission, turn on the engine, and check for leaks. Then another half hour to put everything back. Shop closes at 8 pm.

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This is the most difficult task that I have attempted on the CX-3. But after changing the valve cover gasket on my MINI in early August, I started to feel a bit more at ease. It is pretty much the same procedure, just upside down, and with RTV instead of rubber gasket. Still felt anxious like I was about to take an exam.

The lift/bay/tools rental for 8 hours today plus fluid disposal cost $220 (with early bird discount since I booked in late July). OEM Filter from OEMparts, Aisin fluid from RockAuto, shipping altogether was about $100. I plan to return next week for a half-day ($150) follow-up to check for leaks.

I am not saving a lot of money. I remember reading fellow members' write-up here and the cost by a proper mechanic/shop wasn't much higher. It is the clarity that I need, i.e., knowing what was done, how it was done, no matter how poorly done. 😂
 

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The bottom of the air box is out. To start the engine and check fluid level, I can just connect the top part of the box to the air pipe. The panel air filter is held to the top by a bungee so it won't fall out.
 

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To take the pan off, I pointed the putty knife at the seam and hit it with a rubber mallet. The knife cracked as a resilt. I then used a flat head and mallet. It took only a few light hits at that spot to release the pan, didn't have to go all around the pan. But the flat head nicked a spot where the arrow is pointing. My bad.

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I rolled up a piece of shop towel to prevent any debris from going in the fill hole, it wasn't necessary at all since the pan was coming off. The drain is at the front. The small port on the filter is closer to the front. The large port on the filter is further down/out, that is where we get to see the paper element through an opening on the bottom. I should probably cut open the used filter to see what's inside.

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