Merry Christmas and Happy Newyears for all!

For a 2016 Lexus GS, I believe there are two openings for coolant,
(1) Coolant container/reservoir attached to the radiator.
(2) By thermostat on the engine block.
What I observed today when checking the fluid level, cold engine on a flat surface, I observed that (2) was completely empty, almost dry.
Is that common when cold? or does it indicated some problem?

Note: (1) level always goes below low even after refilling it to between full and low-level mark on the reservoir when cold.

Thanks in advance!

 

#1 at the front of the engine is the reservoir, where you would top off the coolant intermittently. #2 is really used when servicing the cooling system and will look low when the engine is cold.

As the engine heats up, the coolant expands and will overflow the cooling system, hence the existence of the reservoir. When the engine cools, the coolant volume shrinks and the natural vacuum formed "sucks" the overflow from the reservoir back into the cooling system. It is natural for some evaporation to exist and you will have to intermittently top up the reservoir with coolant, but most times it's a minuscule amount and not noticeable.

I would suggest you top off your reservoir and monitor the level for the next couple of weeks (assuming you drive your car daily and there are sufficient start and stop cycles to allow the coolant to move between the reservoir and the engine regularly). Top off as needed and hopefully the level will remain consistent and not require topping off after a few days. If it keeps dropping, there might be a leak in the cooling system (which so far has been pretty unheard of in these cars).

Good luck and report back to let us know what you find. Cheers!

 

Thank you for your input!
The vehicle recently underwent a transmission and trans cooler swap under warranty 5days ago and I just suspect the technicians didn't do a great job of bleeding the system cuz haven't had this problem before the swap.
The reason I'm blaming them is they did a sparkplug job in the past and forgot to put back intake hose resulting in vehicle stalling due to unmonitored fuel-air mixture.

It might not be a bad idea to rebleed the system. The question is should I perform it myself or take it to the dealership.

 

If you're under warranty, let the dealer do it... if it breaks, you don't want them to turn around and have a reason to blame you and deny any warranty work.