If your car is so filthy you can’t even remember what colour of paint you have under that thick layer of grime and salt coating your car, it may be time to bring in a pressure washer.

Using your pressure washer to clean your car’s exterior can be quick, convenient, and yield shimmering results. But there’s also a risk of damaging your paint job, or even your car’s electrical system. Following the right steps and knowing what to watch for are key to a successful wash.

A residential pressure washer. Most electric pressure washers will be adequate for the job, and gas-powered pressure washers may almost be too powerful. Look for a rating of around 2,000 PSI with a flow of above three GPM (gallons per minute).

A nozzle. Use one that concentrates the spray in a tight pattern. A rotating nozzle will cut through dirt more effectively.

Detergent. Use the detergent recommended by your pressure washer manufacturer. Laundry detergent or dish soap could scratch your vehicle.

Hot water. Using very hot water with your pressure washer will help cut through the grease. If possible, use soft water.

A chamois leather cloth. For drying.

A cool day. You’ll get the best results if your car’s surface is cool.
If it’s a hot day, rinse the car with cool water before starting.

1. Prepare your pressure washer. Plug in the power and connect to your garden hose faucet. Connect your nozzle and trigger, and pull the trigger to squeeze out any trapped air. Wait until you have a steady flow of water, then turn on the high-pressure washer function. Test spray in an area away from your car to get a feel for the pressure.

2. Rinse your car. Using a high-pressure setting, knock the dirt and grime off your car with water. Keep the nozzle of your wand at least 20 cm (eight inches) away from the car’s surface to avoid causing damage. Work on a small area at a time, spraying in a consistent motion.

3. Apply detergent. Dilute your detergent concentration to the recommended levels and add it to the solution chamber of your pressure washer. Using a low-pressure setting, coat your car’s surface with detergent. Don’t let it dry on your car.

4. Rinse off the detergent. Switch your pressure washer out of mix setting, or remove the detergent chamber. Rinse your car until all detergent is removed.

5. Dry using your chamois leather cloth or “shammy.” This will leave that nice, streak-free shine.

Pressure washers can cause damage to your exterior or to your tires. Watch out for flaws on your car’s paint job, as you might end up peeling more paint off from that spot.

Be careful not to force water anywhere it shouldn’t go, or to rip off any trim. Don’t aim your pressure washer at your tires for more than a few seconds, as it could damage or weaken your tire sidewalls.

If you don’t have a pressure washer, you can attain good results using a garden hose and a high-pressure nozzle paired with some elbow grease, though pressure washers waste less water.