The 2003 Audi TT is equipped with G12 coolant in the radiator and cooling system. G12 is a specialty blend that Audi calls “lifetime” antifreeze. The only time replacement of the coolant in your TT should be necessary is if you are replacing the thermostat, water pump or similar cooling system component. Purchase G12 coolant from an Audi dealer or specialty supplier, as it is the only coolant recommended for use in your Audi.
Raise your Audi TT with a jack. Secure the car on jack stands before draining the coolant. Make sure the engine has cooled, then raise the hood and open the cap on the radiator.
Locate the coolant drain plug on the bottom passenger side of the radiator and place a drain pan directly beneath it. Loosen the drain plug and wait while the coolant drains from the system. Tighten the drain plug once the coolant has drained completely.
Raise the car with the jack and remove the jack stands. Lower the car to the ground. Fill the radiator and overflow tank with Audi’s G12 lifetime antifreeze.
Start the ignition with the cap off the radiator. Wait for the engine to warm up and open the thermostat. Top off the coolant in the radiator as needed during this process. Once the level remains consistent, turn off the engine and let it cool before replacing the radiator cap.
Check the coolant level again within 24 to 48 hours and top off the fluid as needed.
