2019 Lexus GS — coolant is old by age but mileage is low

This is usually cheaper to test than to guess. Two 2019 Lexus GSs can feel identical and have different causes, so measure before you copy someone else's repair. That's the branch I'd chase this week. I'd want that in writing, not as a promise. Make the next action something you can finish this week. I'd rather pay for diagnosis than a second guess-repair.

Log the conditions before you spend. Capture voltage while the 2019 Lexus GS is actually failing — after it restarts you've lost the clue. Save the big job until that test fails. On “coolant is old by age but mileage,” that was the fork that mattered for me. This is from a 2019 Lexus GS in Tampa. Any freeze-frame data saved? Only after sitting overnight so far.