so my car is about to reach 250k and i need it to last til at least about 300k, so i was wondering what should i do it to it in terms of maintenance?
here's what i am planning to do in the upcoming weeks

-full tune up
-brakes
-transmission fluid change
-oil (just got changed 4k ago)
-tire rotation

is there anything else that i am missing out?

Drain,Flush Cooling system,Inspect hoses,Clean radiator,condenser,pressure test cooling system and pressure cap...An emission control service. The inspection list can go on and on.It all depends on what maintenance you had done in the past.