19k miles and low coolant message pops up.........

[BarryG]

My 17 did the same thing somewhere around 30k miles cant remember if it was summer or winter but thinking it was summer time. I had to add some, wasn't too much hasn't happened again since except when they did the water pump recall somewhere around 50 or 60k then I had to add some more the next day but again not since then now at over 100k miles.

 

[gsbrockman]

could be one of the “Y” pipes in the system that connects the radiators together!

Except the OP has an ‘18 sans dual radiators and y-pipe....

 

[AH64ID]

not needed.

 

[Ozymandias]

I'm the bad guy, i always overfill the bottle and let it level in by itself. To much fluid, off it goes.
After a couple good heat and cool cycles the level stays where it wants to stay.

 

[TDRGuy]

Closely monitor coolant loss.

Suspect part : EGR cooler leak. It is of no concern to performance as the coolant is burned/evaporated instantly. So a slow trickle eventually leads to low coolant level and, if you don't watch the idiot light or notice a high (remaining) water temperature, you would overheat an engine.

RP