90 S5 GTU (automatic..for now) when i start the car up its fine, runs normal everything is fine. but after gettin WARM, and i cruise at 2500 RPMs the add coolant light turns on.
if i acclerate to 4k+ it stops but then starts when it hits 25K for a certian amount of time.
the coolant is full and ive looked/ searched for answers but no one has quite the same problem as i do. and when the alarm goes on it doesnt turn of unless i speed up or slow down, but once it starts it goes off every 3mins or so.

any ideas? ANYONE!

 

air bubbles in your coolant system? when's the last time you lfushed it? did you do it properly and make sure no air bubles were in it?

 

When is the last time you checked the oil?

 

As for the coolant. These cars are notorious about air pockets. A couple of things you can do:
1. With the car off and cold, squeeze the upper radiator hose a few times. "Burp" the system. Then check and see if you can add coolant. You can also try opening up the sensor on top of the radiator to bleed air off.
2. You can pull the thermowax sensor out and add coolant until it runs out of the hole.

 

today i didnt a coolant flush and an oil change, now its going off more than before and at different rpms!, wtf...

any more ideas?