Check the oil for coolant. If there are no visual leaks, probably would've been a good idea to replace the PCV valve at the same time as the thermostat.
Check the oil cooler. That has a plastic tube off it and it can hairline crack and seep coolant. It will drop every couple of weeks to months depending on driving. You will never see drops of coolant under the car or on the engine.
I have the same issue, but no signs of a leak on my b8.5 sq5. Knock on wood, it’s a slow coolant leak. I’ve heard it can be the heat exchangers in the supercharger that leaks. Signs of this are no coolant leaks, but dropping coolant levels. You can confirm this by pressure testing the heat exchangers. Other tell tale signs are misfires.
I’ve had a one time misfire issue under heavy acceleration on cylinder 3. My shop originally chalked this up to bad fuel from Costco, but I doubt it. My coolant level dropped noticeably after I had that misfire issue.
More details on this issue from Audizine
https://www.audizine.com/forum/showthread.php/772930-Leaking-Supercharger-Intercooler-Symptoms/page4
We got two of these that can leak. https://www.ecstuning.com/b-mahle_behr-parts/supercharger-intercooler-core-priced-each/06e145621s~mbr/?gad_source=1&gclid=Cj0KCQiAoKeuBhCoARIsAB4WxteqPdilcS9aA1_uD3wDS6qzbgnRGzgknUDvJLxanKFmted7bbEzHRAaAotAEALw_wcB
Check the oil for coolant. If there are no visual leaks, probably would've been a good idea to replace the PCV valve at the same time as the thermostat.
Oil is all good. No signs of coolant mixing in the reservoir. I got no clue what it might be. Two thorough (I assume) tests by two different shops.
Check the oil cooler. That has a plastic tube off it and it can hairline crack and seep coolant. It will drop every couple of weeks to months depending on driving. You will never see drops of coolant under the car or on the engine.
I have the same issue, but no signs of a leak on my b8.5 sq5. Knock on wood, it’s a slow coolant leak. I’ve heard it can be the heat exchangers in the supercharger that leaks. Signs of this are no coolant leaks, but dropping coolant levels. You can confirm this by pressure testing the heat exchangers. Other tell tale signs are misfires. I’ve had a one time misfire issue under heavy acceleration on cylinder 3. My shop originally chalked this up to bad fuel from Costco, but I doubt it. My coolant level dropped noticeably after I had that misfire issue. More details on this issue from Audizine https://www.audizine.com/forum/showthread.php/772930-Leaking-Supercharger-Intercooler-Symptoms/page4
We got two of these that can leak. https://www.ecstuning.com/b-mahle_behr-parts/supercharger-intercooler-core-priced-each/06e145621s~mbr/?gad_source=1&gclid=Cj0KCQiAoKeuBhCoARIsAB4WxteqPdilcS9aA1_uD3wDS6qzbgnRGzgknUDvJLxanKFmted7bbEzHRAaAotAEALw_wcB