When trying to keep a VW Passat in top operating condition, it is necessary to perform routine maintenance, including flushing the radiator. If you can operate a wrench and follow directions, then you can complete this maintenance with relative ease.
Park the VW Passat on a flat surface and set the parking brake. Then, pop the hood and check the external temperature of the radiator. If cool, you can proceed, otherwise, allow the radiator to cool off before you move on to the next step.
Twist the radiator on full turn to relieve any leftover pressure. After a few seconds, completely remove the radiator cap.
Place a bucket or tray with at least a 2-gallon capacity underneath the radiator and below the drain plug. The drain plug should be on the front lower driver's side of the radiator in the VW Passat.
Remove the driver's side bumper panel on the front of VW Passat to gain access to the drain plug. The panel should just pop off. Use a socket wrench to loosen the drain plug. Then, allow the existing coolant to drain completely into the drain bucket.
Pour the old coolant into a sealable container for proper disposal and put the bucket back underneath the radiator.
Close the drain plug and fill the radiator with distilled water. After a few minutes, open the drain to allow the water to flow into the bucket. Keep repeating this process until the water is free of any debris. It takes at least 3 gallons of distilled water to flush a radiator properly.
Put the drain plug back into place and dispose of the flush water. You will need about 2 gallons of distilled water to complete this task.
Fill the radiator with fresh coolant to within an inch of the lip. Then, start the car and allow it to run until the cooling fan turns on twice.
Turn the car off, check the coolant and top it off, if necessary. Finally, put the radiator cap back on and close the hood of the VW Passat.
The manufacturer recommends that you use G12 plus Coolant for the VW Passat. You can use tap water instead of distilled, but tap may leave sediments behind that can damage the coolant system.
Coolant is very toxic to humans and pets and you shouldn't drain or dispose of it in an open area. Instead, take the used coolant to a liquid waste disposal site or a local auto repair shop.