Sorry kiddo, but you're not the sharpest knife in the drawer. Go look at your coolant. If it's colored it's fine If it's clear, add antifreeze. On a car that new it should have antifreeze in it, but the dealer is right, you should have had the system flushed and refilled. That's called preventive maintenance and should be done once a year. 2 years maximum if you're a cheapskate. In fact, anyone buying a used car from a dealer could have easily negotiated a radiator flush as part of the deal or no sale. FAIL.
A clue. Get one. Life will be easier.
· 3 months ago