I have a 2008 GTI, FSI (BPY) with just about 160k miles. Over the past 2 months I've been noticing the level in the coolant reservoir slowly going down, requiring me to top it off roughly every 2 weeks. Also around this time it seems like the car started to slightly smoke white at idle. I've never noticed any smoke behind me while driving, no CELs or faults, driveability hasn't changed nor has the coolant temp ever gone past 190F, or overheated.
I'm not sure where the coolant is going, I haven't noticed any external leak or really smelled coolant. Reservoir is clean and appears to only contain coolant. I don't know how significant this is, but I've only had G12/G13 in the system. I religiously check my oil, as everyone should
and also have not noticed any milky substance on the dipstick or any mixture when I did my most recent oil change, roughly 200 miles ago. Nothing under the oil cap either. Has anyone ever ran into an issue like this? I still haven't done a pressure test on the coolant system so that could be my next move but if I find nothing I'm lost.
Since owning the car I've done some work. In terms of the coolant system, I've changed..
-OEM water pump to INA metal impeller water pump during timing belt change
-New washers for coolant lines to the turbo when I went K04
-4 way distribution pipe on the upper rad hose due to nipple breaking off
Leave your thoughts and inputs, I'm looking for some guidance.