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As the name suggests, pressure washers are used at high pressure to get rid of challenging stains on your car. This method is even considered to be more effective than hand washing or waxing your car’s exterior. At the same time, this ensures that your ride is always attractive and makes it last longer.
Unfortunately, if the water pressure is so high, this technique might end up damaging the car paint and other parts. As a result, pressure washing may remove the paint and expose the metal below, thus exposing it to rust damage. To avoid these potential risks, Consumer Reports does not recommend the use of pressure washers to clean cars.
Don’t worry though! In this article, I’ll show you how to properly use the best pressure washer for cars to get rid of dirt, grime and stains without damaging the car paint.
Can pressure washers damage car paint?
When used properly, pressure washers will not damage car paint or remove sealants and waxes. Besides, considering sealants and waxes aren’t water-soluble, they’ll not degrade or break down when sprayed with water at the right pressure.
So, if you want to remove the wax from your car’s paintwork, pressure washing will not work. Instead, you should look for another product that is specifically designed to strip the wax such as traffic film remover and paintwork cleanser.
However, if you pressure wash your car at extremely high pressure, the risk of damaging the paintwork is quite high. For instance, some commercial power washers are so powerful as sand blasting machines that they can even strip engine components back to raw material.
Such power washers are not ideal for use on cars as they will harm the paintwork.
All in all, pressure washers for car washing are only intended for home use and are only powerful enough to get rid of grime and dirt after rinsing and soaping your car.
More importantly, you should avoid exerting too much pressure as it can cause small scratches on the car’s surface, causing water to accumulate and make the car rust.
So, even if you’ve got the right pressure washer for cars, it’s important to ensure that you’re using the right settings to avoid damaging the paintwork.
What’s the safe PSI for washing cars?
An electric pressure washer with a pressure output of 1200 – 1900 PSI is perfectly safe to use on baked-on paintwork of all modern cars, even at the high end of the PSI scale. In contrast, classic cars are more sensitive to the use of pressure washers since their paintwork was applied using different processes.
Also, exceeding a PSI range of 1900 may harm your car’s paintwork, even for modern cars. For that reason, you should consider using a pressure washer with a flow rate of 1.4 to 1.6 GPM.
There are 2 measurements you should consider when determining whether a pressure washer is effective at cleaning your car; the GPM (Gallon Per Minute) and PSI (Pounds per Square Inch).
PSI or Pounds per Square Inch refers to the power of a power/ pressure washer, while GPM measures the amount of water that passes through the device per minute.
Gallon Per Minute
Typically, a garden hose allows 5 to 10 gallons of water (GPM) to flow through it per minute at an average pressure of 30 – 50 Pounds per square inch (PSI). In comparison, a light-duty residential pressure washer has a flow rate of 1.6 GPM at a pressure of around 1750 PSI.
The cleaning power of a pressure washer can be calculated by multiplying the GPM by the PSI. For instance, if a garden house has a GPM of 5 and a PSI of about 50, its cleaning power is around 250 Units.
On the other hand, a pressure washer with a flow rate of 1 -2 GPM and a pressure output of 1500 PSI, delivers a cleaning power of around 3000 units.
This means that a pressure washer has 5 to 18 times the cleaning power while using 68% less water. Therefore, the best pressure washer for cars should have a PSI range of 1200 – 1900 PSI and a flow rate setting of 1.4 – 1.6 GPM.
Other factors to consider when buying a pressure washer for cleaning cars
Contrary to what most car owners believe, washing a car with a pressure washer involves more than delivering a steady, high-powered stream of water from a hose. For that reason, there are several factors you need to consider to avoid stripping off the car’s paint. Some of these factors include;
Apart from GPM and PSI, nozzles are another important factor you should consider before choosing a pressure washer for washing cars as they’re responsible for distributing the water coming from the device. Nozzles for pressure washers are available in various sizes ranging from 0 – 65 deg.
In general, nozzles with lower angles deliver a direct, targeted stream, making anything above 15 degrees ideal for applying soap or rinsing off a car. On the other hand, anything below 15 degrees is too strong for the paint.
In addition, it’s important to choose the right type of nozzle for your power/ pressure washer. Using the wrong nozzle type can increase the PSI to a dangerous level, thus increasing the risk of damage to the car’s paintwork.
For instance, narrow nozzles create more pressure since they concentrate water to a small surface area.
While this is great for cleaning, using pressure washers with the wrong nozzle can damage the car paint and the protective coating (wax/ sealant). A fan-type nozzle is the safest option for washing cars since it applies water to a larger surface area, hence reducing the pressure.
|Degree of Nozzle||Color of the Tip||Application|
|40||White||Ideal for cleaning car surfaces since they’ve low pressure and cover large surfaces.|
|25||Green||Used to pre-rinse, remove mud from the car and clean tire rims/ truck beds.|
|15||Yellow||Commonly used to remove paint from walls|
|0||Red||Ideal for cleaning cement and surfaces as they have huge pressure. However, this type of nozzle is not recommended for cars as they can damage the paintwork.|
Electric Vs Gas-powered pressure washer
Generally, gas-powered pressure washers usually produce more power than their electric counterparts. For that reason, an electric pressure washer is recommended for washing cars to reduce the risk of stripping off the paint.
Also, gas-powered cars can be overpowered, thus generating PSI that could crack the car’s windows. At the same time, gas pressure washers require much more maintenance and are usually more expensive.
How to safely use pressure washers without causing damage to the car paint
Now that you know the factors you should look out for when choosing the best pressure washer for cars, here’s how you can safely use it without damaging the paintwork;
Clean dirt & debris
Before you start pressure washing your car, it’s a good idea to wax and touch up any rust spots and paint chips. Next, rinse off the car to get rid of the top layer of dirt and any large chunks of mud using one of your wider spray nozzles.
More importantly, avoid using a concentrated or strong spray nozzle while the dirt is still on the car’s paintwork. At the same, be extra cautious while spraying around delicate parts like headlights.
Use soap or a cleaning solution
Use the inbuilt detergent container and the soap/cleaning solution recommended by your car maker/ pressure washer manufacturer to thoroughly spray detergent foam over the whole car.
Let the cleaning solution sit on the paintwork for a while. This gives the solution enough time to loosen any dirt particles and break down grease & grime. Next, gently brush over any areas with dirt with a brush attachment from the ground up to avoid streaking.
Main spray wash
Switch to a high-pressure nozzle & spray pattern and use the pressure washer to rinse off the loosened dirt. Work in constant fluid movements while keeping a safe distance of about 1 – 1.5m between the paintwork and the nozzle to avoid damaging the paint.
Also, avoid lingering in one spot for too long and pay close attention to the wheel arches and wheels where the most dirt can collect.
Dry the car’s surface
Use high-quality chamois leather to dry your car after pressure washing to avoid streaking. Chamois leather is extremely absorbent and very soft, so it will not cause any problem to your paintwork provided they are free from dirt.
That said, use uniform movements to pull the chamois leather downward over the car’s surface or toward you until it’s soaked. Ring it out and repeat this over the entire car until it is completely dry.
Once the car is completely dry, you can now wax it to protect the paintwork from dirt, grime, and water ingress when you hit the road.
Overall, pressure washing will not damage your car’s paintwork if you choose the right type of device and use it correctly. In addition, you should adhere to the rules I’ve mentioned above including setting the pressure washer at the ideal PSI to safely wash your vehicle for several years to come!
Read Next: Best auto shampoos for pressure washers.