Can You Use Normal Car Shampoo in a Pressure Washer?

If you recently bought a pressure washer, big congrats to you. You have just made washing your car easier. You probably have formulated plans to wash your car for the first time with your new machine and can’t wait to drive around your clean car. The anticipation and joy is overwhelming and you can’t get it out of your head that you would be driving a very clean car to work daily. That is if you wish to wash your car on  daily basis. 

Since you are upgrading from washing cars with your hand to washing with a pressure washer, there are things you need to know. These things can either mar your washing experience or make the experience worthwhile. The reality is there are some things that go well with washing cars with the hand that don’t go well with washing with a pressure washer. So you need to drop the old habits and adopt the new ones. 

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The big question you might be asking is can you use a normal car shampoo with a pressure washer? You know it’s possible if you are washing with hands, but is it possible with a pressure washer? This article will discuss this possibility, and whether or not, a pressure washer can maximize the chance of using a shampoo to make your car cleaner. 

What is a car shampoo? 

In a simple way, a car shampoo is a cleansing product, composed of surfactants that is used for removing dirt. A car shampoo is composed primarily of two-molecular chains, one that has affinity for water and the other, for dirt. When you apply it to a surface like that of a car, the active ingredients inside surrounds the dirt and try to get rid of them from the surface in a suspension of water. It is this water that rinses them away. A car shampoo can remove many dirt, debris, and soiling from its surface. 

Car Shampoo and Pressure Washers

First of all, you need to know whether or not pressure washers have any provision for the use of car shampoos. Fortunately, most pressure washers come with specific types of detergent tanks. These tanks are designed to be filled up with detergents that are meant for washing cars. Since most car shampoos are designed to be applied on a surface before you wash it off, you can’t really use it in a pressure washer detergent tank. That is because during the process of washing, a lot of bubbles and foam will be formed, which could be detrimental to the nozzle of the pressure washer. Incase you are asking whether detergents and normal car shampoos are the same, well they aren’t and we will state reasons why they aren’t the same thing.

Normal car shampoos does not need to be diluted because it’s already semi-diluted. Detergents, on the other hand needs to be diluted before you can use it to clean your car. The detergent will mix with pressurized water in the pressure washer tank and be discharged through the nozzle. Most car shampoos does not work that way and that is because there is no way you can dilute something that has already been diluted. Remember, we made mention of bubbles and foam forming when you use a shampoo in a pressure washer. Detergents, on the other hand won’t create so much bubbles when you use it in a pressure washer. 

So can you use a normal car shampoo with a pressure washer? 

In essence, most normal car shampoos won’t work in a pressure washer. Normal Car shampoos are designed for manual applications and not to be used with a pressure washer. However, there are some normal car shampoos that may work with pressure washers. But for the most part, they are incompatible. 

What kind of detergents work with pressure washers? 

There are several cleaning agents in the form of soaps and detergents that are used for cleaning cars. Karcher Car Wash & Wax Soap for Pressure Washers is an example of a detergent that can be used for washing a car. There are also multipurpose ones like Krud Kutter House & Siding. However, not all soaps and detergents are made for pressure washers, such as the normal car shampoo that we talked about in this article. 

You may ask, which is better between using detergents and soaps? Which one will a pressure washer work with better? Well! It depends on the user and the type of water. Detergents contain synthetic chemicals that are used specifically for killing stubborn dirt, mold, etc. Detergents readily foam in all types of water, including hard water. Soap, on the other hand finds it difficult to form lather in hard water. Soaps are detergents that contain oils and fats. When these two natural ingredients combine with an alkaline solution above room temperature, soap is formed.

The synthetic chemicals in detergents are harsher than that of soaps – this makes detergents more potent in eliminating germs and dirt than soaps. 

How does pressure washers work with detergents and other cleaning agents?

There are two techniques or methods to consider here – upstream water flow injection and downstream water flow injection. Some pressure washers have their detergents run through a pump which is called the upstream injection. Other pressure washers do not run their detergents through a pump itself. This process introduces chemical into the water system after the pump. The chemicals are applied at low pressure, so the chemical do not pass through the pump. 

The issue of whether upstream is more effective than downstream all boils down to preference. Some people prefer downstream because they can use a wide range of detergents. Others prefer upstream because the technique allows better mixing and dilution of certain chemicals. 

If you plan on using the downstream injection method, you will need a soap nozzle. Then, you will have to attach detergent container directly under the nozzle so that it doesn’t mix with the water until it proceeds out of the nozzle. 

Another important point to note is there are specific detergents that go well with cold water and those that go well with hot water. In other words, there are some pressure washers that can handle cold and others that can’t. To avoid damaging your pressure washer, ensure that you use the right type of detergent. You will easily know by their lather. Detergents that are meant for hot water won’t work for cold water and ultimately won’t foam well. 


A normal car shampoo isn’t cut out for use with a pressure washer, even though some users did take a gamble to dilute it with water. In the long run, it ended up damaging their pumps. If you still want to use a normal car shampoo, you will have to apply it manually on your car and then use your pressure washer to rinse. Other than that, opt for detergents and soaps. 

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