Lexus Coolant Exchange and System Flushing 

Another downside of using antifreeze as an engine coolant is that it's a horrible pollutant and bad for the environment. As such, it can't simply be drained on the ground and then have the technician proceed to refill the radiator with fresh coolant. Antifreeze has to be properly contained and disposed of before the system is refilled with fresh new coolant. In some cases, as determined by an experienced technician who understands how the coolant system works, the system may need to be flushed through with clean water a few times before adding the final batch of antifreeze, which will fill the system and work for years to come. 

Does Lexus Engine Coolant Need Replacement?

Your Lexus's coolant is in a fairly well-contained system, the cooling fluid runs through the motor block to cool the heat produced by the friction of pistons stroking up and down in response to the spark plugs firing off shots of electric energy. Energy produces heat, and the engine is engineered to run at a certain temperature; the coolant system moderates that temperature. Unfortunately, over time, antifreeze can break down at a molecular level in response to the continued cycles of heating and cooling it goes through. Alternatively, the fluid can become corrupted. Perhaps the coolant level is low, so the car owner adds water, or debris and grime from regular driving infiltrate the system. These things are normal and happen over time, but lead to the need to drain and refill the system on occasion.