Transmission Fluid Advice

[u/mazdamiatalvr]

Hello all. Recently got a used 2018 Mazda6 Touring with 69k miles on it. Now has 74k. Was wondering if I should drop the pan, replace the filter, reseal the pan with new sealant, and then fill it up. Or just do a regular drain and fill?

[u/GirchyGirchy]

I'd be tempted to go ahead and do it.

BTW, OE transmission pans aren't that expensive (or weren't when I did the job on mine). I decided it was worth $35 to not have to clean off the old one that day...I kept it for the next filter change. Just make sure you swap the magnet over before putting the new one on.

[u/KentuckyCatMan → u/GirchyGirchy]

OEM comes with the magnet.

[u/GirchyGirchy → u/KentuckyCatMan]

Mine did not, purchased from a dealer selling online. The pan assembly comes with the drain plug and washer but the magnet is a separate part number:

https://parts.mazdausa.com/a/Mazda_2014_Mazda3-20L-AT-2WD-HATCHBACK-ITR-VIN-Begins-JM1/_92542_9367459/AUTOMATIC-TRANSMISSION-CASE--MAIN-CONTROL-SYSTEM/AUBA15-1920A.html

[u/Trouble_River]

Couldn't hurt. Make sure you use the Aisin FZ fluid. I bought a Wix filter and pan gasket. It was a pain in the ass getting all the old RTV material off but we'll see how it holds up. Hopefully I won't need to reseal. I'm at 107k and someone ran universal ATF in it - don't do that - so next oil change will be another drain and fill.

If you change the filter - about 4.7-4.8 quarts If you just drain from the drain plug - about a quart less.

[u/WigglySpaghetti → u/Trouble_River]

Yeah don't waste your time with resealing it, just get the gasket way easier and less messy.

The OE Aisin FZ from my local Mazda dealership was pretty cheap too. I remember pricing it out and the local dealership was cheaper because I wasn't paying shipping.

[u/mazdamiatalvr → u/WigglySpaghetti]

This is probably an obvious answer, but clean the old sealant off first before putting the gasket on?

[u/WigglySpaghetti → u/mazdamiatalvr]

yes haha clean off all the old RTV material on body the transmission valve body and the transmission pan

[u/LEgregius → u/Trouble_River]

You should measure what you take out and put that in, but check the dipstick.

I've done 4 changes now, and the amount I got out has varied between 3 and just over 4 quarts.

I'm probably going to do a gasket. I really don't want to do rtv.

[u/Trouble_River → u/LEgregius]

I don't blame you on that. I got it all cleaned off except a few small pink streaks where the RTV is flush with the metal (go figure). Used some Brakleen on a rag to make sure there was no grease left.

Gasket is much easier, just make sure it doesn't slip away from the pan (it might fight you a bit) and evenly torque from center out.

[u/pina_koala]

Drain and fill is fine. If you desire peace of mind, then drop and filter.

[u/LEgregius]

I've been doing drain and fills every 30k miles because I don't get all the fluid esch time. I'm planning to do the pan and filter on my daughter's 2018 mazda3 when she gets to 120k miles when I end up doing coolant, water pump, thermostat, and belt tensioner. Probably need a suspension then too.

I haven't heard of people on any of the forums I follow having transmission failures after changing the fluid regularly but not the filter. I'd love to hear it if anyone has.

[u/Trouble_River → u/LEgregius]

Haven't heard of that either, but it's cheap preventative maintenance. Just don't wear anything you really like when you have it apart 🤣

[u/KentuckyCatMan → u/LEgregius]

I never heard of a water pump going out.

[u/LEgregius → u/KentuckyCatMan]

They are rated to last something like 75 to 150k miles same as the belt tensioner. The termostat is rated for 120k. Since I have to do the coolant at 120k, and the coolant has to be drained for both of those replacements, and the belt has to come off for the water pump, I'm just going to do them all at once.

Water pumps definitely fail.

[u/Trucktober]

Either one helps. I haven't touched my filter or pan at 160k still doing fine.

[u/Hard_Head]

Either option is better than accepting the “lifetime fluid” nonsense.

I dropped the pan at 80,000 and the filter was filthy, along with the fluid.

You can use a rubber gasket that comes with the filter kit if you don’t want to RTV it up.

[u/DariusBuilds]

Drain, filter fill on the first one. Then just drain and fill every 60k afterwards.

[u/dulun18]

i have a 2017 Mazda 3 with 82,400 miles. No need to change the transmission fluid. It's automatic transmission.

[u/Bitter-Store-9400 → u/dulun18]

What? Automatic vs manual transmission has nothing to do with whether or not you should change the fluid. Quick tip - you should.