2015 Mazda6 (2.5L Skyactiv, 6 Speed Auto) Update at 284,000KM

Skyactiv 2015 Mazda 6, 2.5L NA, Custom 91 Octane Tune
Hi all, This Mazda has been in my family since new. I have acquired it 3 months ago after my dad upgraded to a 2023 Camry.

As the title suggests, the car has over 284,000KM on it, maybe 60% city driving. The car has an extensive maintenance history. The only thing which hasn't been done yet according to maintenance schedule would be the fuel filter.

Oil changes every 5-7500KM with only oil filter change at 3-4000KM (I use 5w30/5w40 in winter and 5w40/10w30 in summer)
Three full transmission services (filter and fluid change, car will be going in for its fourth transmission service at the end of this month)
Front control arms and one of the tie rods needed to be replaced earlier this year. The suspension is in fair condition for the mileage
The serpentine belt was badly worn and required urgent replacement one year ago. You can check for sounds of worn belts during a cold start idle. Rest of the belts appear to be in good condition
Full coolant flush. Turns out the mechanic shop used some sort of Prestone Asian car blend. It was also green in colour. No issues...
Original brakes lasted until 160,000KM.
Spark plugs have been replaced twice
The only real issue to note would have been a seized parking brake. No points against Mazda. These cars were never designed to be used in regions with extensive salt use in winter.

Now.. I know that the ECU in these engines apparently are not designed to be used with premium "91 octane" fuel. Ever since 277,000KM, I have only used ethanol-free 91 octane fuel in this car. The more I drive this this fuel, the more I notice my fuel economy and overall engine performance continues to improve. Power output has improved subjectively speaking. I can confirm this because the transmission now shifts at a hair under 6000RPM when going full throttle (without kickdown). Before, the transmission shifted at 5500RPM in first gear and no more than 5700RPM in second or third.

I have managed to achieve an amazing 5.8 or 5.9L/100KM (Better than even the EPA estimate) in highway driving, with no wind on a flat surface. I average 6.2L/100KM in a mix of highway, county one lane roads and some city driving in busy Greater Toronto Area. The increase in fuel economy as compared to before has easily paid itself off in contrast to using regular ethanol blended fuels.

Overall, I am exceedingly happy with this car. The car is quite responsive and very engaging around turns. The chassis balance for FWD is phenomenal. The only real complaint I can think of would be the seating position. I am 6'4. Getting the seat a bit lower would be nice. The seat feels tight around the bolsters, but it is very comfortable and supportive. Head room is lacking when sitting passenger. Leg room is excellent in the back seat, even sitting behind myself.
Thought I would make an update after having the pan dropped in this car for the fourth time.

The shop said they suspected that a different transmission fluid was used from what Mazda recommends. Could just be a change in colour from driving use. The transmission was shifting totally fine. Unfortunately the car was driven about 30,000KM without a magnet in the pan! A spare one was added in. Ultimately the bottom of the pan had minimal sludge. The filter and fluid was a bit dirty. Only about 4L of ATF fluid went back in. Shift points are a bit more precise, faster and more precise shifts, especially when accelerating at high RPM's, but no significant difference as the inside of this transmission was already pretty clean to begin with.

To conclude, I would suggest to have your pan dropped once every 60-80,000KM. Past 100,000KM you start to push the overall longevity of your AT. Expect overall life span of your transmission to be significantly impaired past 200,000KM. The first pan drop should typically be done closer to 60,000KM due to extra metal shavings breaking off the transmissions internals during the initial wear in process early on the gearbox's life.

If you are doing the pan drop after 100,000KM, I would recommend doing one or two drain and fills afterwards to make sure that most of the fluid in your gearbox is clean. You'll get significantly restored shifting performance.
I have heard that the belt tensioners can be problematic on these vehicles? I am at 311,000KM. Since updating this thread, I have replaced both front end links.

What else should I be looking out for? I am on the original starter and alternator. How long can i expect them to last?