Just bought a 2008 Mazda5 with 128,000 miles. Got it from a small used car lot that purchased it a few days before from the Classic auto group dealer-only auction here in suburban Cleveland, a large, multi-brand new car dealership. The car seems to run well, shift smoothly. Engine oil looks fresh and golden and has a new filter and serpentine drive belt. But I haven't checked the transmission oil yet for color or smell but am planning on driving about 1,300 miles back and forth to New England next week. I was wondering if it would be advisable to change the trans fluid and replace the strainer/filter unit?

If I do, I would NOT ever power flush the trans but instead do it old-school by draining the pan via the plug, then putting the plug back on and refilling the trans, disconnecting the trans cooler line, putting on a plastic tube and then running the motor for a few minutes to drain the old fluid from the torque converter while adding new fluid via the dipstick tube until the color is bright and clear. Then I would drive the car for a few hundred miles and repeat the procedure, only this time I would drop the pan and change the strainer/filter first, reinstall the pan and gasket. And I would only use OEM Mazda Type 5 fluid or the Idemitsu Type M fluid.

So my questions are:

1.) if the fluid looks black and dirty, should I do a fluid and strainer/filter change the way I described?

2.) when I drop the pan and change the strainer/filter, what is the difference between the Mazda dealer's OEM part (#FNC121500A) which wholesales for $70.65 and the auto parts store units from Fram, NAPA, etc... which sell for around $20?

3.) I know the original pan gasket was an RTV silicone sealant but today the strainer/filter kits come with either a rubberized or cork material pan gasket. Which of these 2 gasket materials is the best way to go, assuming not using RTV silicone?

Really appreciate you opinions on this as I want to be proactive but don't want to open up a can of worms for trans problems in doing so.

And what other things do you suggest I look at to thoroughly inspect the car and make it better?

THANKS!!!!!

 

Heres the way I feel about it. Transmission oil change costs 100 dollars or a little more. New transmission 4-5 k. I would rather spend more on oil change than buy new transmission. I also change fluid every 30-40k regardless of what experts say. Dont wait for oil to turn black. Just my opinion

 

It does not hurt to change the filter, and if by chance it has a lot of stuff in it, it might boost your line pressure a tiny bit and keep the transmission alive longer. On most transmissions there are also magnets to clean as well. Remember that bits of metal are what make solenoids jam and bits of grit Tutuapp 9Apps Showbox are what mess up the valve body, so the cleaner it is the better.

 

This is not an opinion but fact and experienced based from servicing many transmission over a few decades.

Doing a filter service will help you get a better idea how the transmission is. Nothing more. It will give you a idea what you may want to consider to do when you get home.
Changing the fluid will not increase any pressures in the valve body.
If you use a gasket you will need to decrease the torques value and re-check the bolts after a few hundred miles. Technically it is better to use only sealer again but many seem to have difficulties apply the sealant alone and have it successfully seal. That is why many service kits come with a gasket.
There is no filtering quality difference between a OEM and most brand name filters for a transmission.
The color of transmission fluid no longer the best or truly accurate means determining the state of contamination as it once did. New MAZDA's after about 3-5k miles fluid will and does look dark in color.
Smell of fluid still has some bearing on clutches for burning but in many newer transmission this way of determination of fluid quality is not as accurate as it once was.
The only real way to know what is going on is with an oil analysis of the transmission fluid.
If you plan on keeping the vehicle it is a well worth investment. With that you can decide on to do a complete proper transmission fluid service replacement. There is so much miss understanding about a pressure fluid service mostly from shops that did it incorrectly further damaging a transmission that was already ready to die.
The pan magnet will catch metal partials of iron and steel not aluminum and there will always be something on a magnet more so with a high mileage transmission that was never serviced. The transmission has wear in when it is new and you can and often see magnet caught metals if you do a transmission service even at lows mile like 3-5k miles. Unless the filter was completely plugged it is less likely that any metal will continue to flow through the transmission. That's why there is a filter and a magnet in the pan.

ASE

 

i have always every 2 to 3 years on Toyotas changed tyranny oil and filter. Cheap and never had any issues. Used gasket on pan as well as liquid gasket sealer to hold gasket in place so it does not move before putting on tranny. Just do it. Cheap insurance. Just brought cx 5 so never worked on Mazda before.