A good quality system such as my Lexus, coolant never lost

I just need replace it on schedule.
酷冷掉了？要麽係統管路滲漏；要麽參於燃燒…
Google: Antifreeze doesn't evaporate but the water does. The reason is that the antifreeze contains several chemical components (80-95% ethylene glycol) that do not evaporate. However, if antifreeze is exposed to the air, it will evaporate over a period of time.