[BlueberryPie]

Sorry in advance for the longwinded question...

I've had a 2019 M240i for 1 year now, purchased with 26k miles and now around 36k. I've never had any coolant warning lights go off, but decided to check the level a few months ago - it was below MIN on the main expansion tank (engine cooled off over night).

Over the last few months, I've topped off the main expansion tank a couple of times as it always seems to go below MIN (engine always cooled off over night before checking). However, it's never gone low enough to trigger a warning light. Is it possible I'm just overfilling it (even though I'm stopping below MAX) and it keeps venting out the excess coolant? I did replace the cap a couple of months ago but still experienced the same behavior. I decided to stop filling it up a month ago and it seems to be staying about the same place - below MIN though.

Secondary question - I've noticed in the main tank only, that there have always been some blue flakes/specks on the yellow MIN/MAX indicator piece as well as floating in the tank. I do not see these flakes in the secondary tank, but I'm pretty sure those two systems don't interact with each other. After cleaning a slight bit of crust off from around the cap, it has pretty much stayed clean. Any insight is appreciated!

Still under CPO warranty, but the dealer was not very impressive during my previous visit. I asked a few questions regarding the coolant to the service rep and a tech but didn't get any solid answers. I do wonder if I were to have never added any extra coolant, if I'd still be around the same level..

This pic was taken a few months back when I was still trying to keep it between the level indicator.