R36 coolant use

[GC0001]

Do any R36 owners here have to top their coolant up?

Since new i've had to top mine up, not huge amounts, just 10-15ml here and there. Its been pressure tested numerous times and all is ok and a new gearbox then fitted under warranty due to that failing-possibly due to the heat exhanger putting coolant into the 'box.

Done a few thousand since the gearbox was fitted and its dropped again, albeit only slightly. I've been told it shoudn't drop at all....

[ACTR36Wagon]

I have not had a problem with my R36 but my previous car (Audi A4 1.8 Turbo) had a slow (but fast enough to be a pain) coolant leak.
Eventually they put a UV fluorescent dye in the coolant and were able to find the leak. The dye shows up under a UV light - so you run the car for a few weeks and then they have a look using the UV light. With mine the bottom plug was leaking under sustained pressure. It would pass a pressure test, but still leak very slowly when driving. The fix was to replace the plug with another one
I suggest you ask them to dump some of the dye in the coolant, and book it back in to be checked in a few weeks time.