147 Coolant level
I've changed the thermostat when I got my (used) 147 few months ago. The mechanic put new coolant (Green Paraflu with distilled water).
He said that probably the level would drop a little within the next days/weeks due to trapped air and to check it with the car completely cold overnight, and to fill up with distilled water. Indeed, within few days it fell around the middle of min/max, and I topped it up.
But the same thing happened around 1000kms after, and once again after around the same.
The past weekend I did a very hard trip, with extreme heat, highway speeds, ac full on all the time, and lots of hill climbing. I did around 800kms. I topped the coolant before going on the trip, and now that i returned the level fell again a little higher than the middle.
It seems to be proportionate to the usage/kms/time the car is working, and not something leaking all the time or when the car is off. The quantities I've had to top were also very small. I'm guessing under 200ml in total for 4 fill ups in 4 months and 4000 hard kms.
What could be the problem? The car is from 2004, and I don't thing the radiator was ever changed. I read about 5year lifespans of radiators here, but I think that's a little extreme. My previous car was 22 years old and never had a radiator change, and the coolant level didn't move at all.
Anyway, should the coolant level change at all? Whats the prime suspect? Leaky radiator? Cap? Hoses?
The car will go for a major service (belts, water pump etc) in September. Is it safe to drive until as long as the level changes are within the min/max range? (I think it gets to the middle and sits there after that, I will probably won't fill it up this time unless it falls under the MIN.