update: so when i first got my car back the overflow tank was 50% full cold, now its down to 10% cold over 100km span...it went up to 25% at hot, seem like there is a leak because i keep smelling coolant(since 2.5k now 5.4k) at my driver side vent, could be heater core leaking or something, gonna drive around more and see if it drop anymore.