Dunno why the caliper froze. It has 48K miles on it.
I did a *half* flush back around 5-7k when I switched over to axxis pads. I added the SS lines so I ended up bleeding all 4 calipers. It also had the *2* years brake flush per dealer maintenance, and the last flush was back in March of this year.

Dunno if it was bad luck, but as you I do live in the Northeast....which may play more of a part with the calipers.

Microfilter I change every year....it's not a cost issue for me and NYC air quality is terrible.

Fuel filter....I would think it can go a longer ways, but if time allows, I may do this and the sparks.

For those who may come across this in a search, I would also consider the crankcase hoses . Myself, I'm not going to worry till it throws a code, etc as I have a extended warranty and I'll let the shop deal with that...