Why is WD40 used in car engine?

This blog post will answer the question, ‘ Why is WD40 used in car engine ?’, and cover topics like how to clean a car engine using a WD40, various uses of WD40 in a car engine, and criteria for selecting the best engine cleaner.

Why is WD40 used in car engine?

These are the following reasons why WD40 is used in a car engine:

  • They help in washing off persistent waste like grime, droppings, and dead bugs from the car windshield or car grill.
  • Cleans dry mud stains with ease
  • Helps to clean oil stains from various car parts and even from clothes in case of oil spillage
  • They are useful in removing scuffs that appear on the paint coating
  • Helps in cleaning the sidewalls of tires

How to clean a car engine using a WD40?

WD40 is a degreasing and deep-cleaning agent used to clean persistent dirt, debris, and gunk from a car engine. It is also a popular product used to protect several delicate metals and electrical components of the car by forming a protective layer over them.

These are the following steps to be kept in mind in order to clean a dirty car engine with a WD40.

Disconnecting the car battery and preparing the engine for degreasing

Disconnecting the battery and other electrical components is necessary as degreasing them can cause a short circuit. They should be covered by a plastic bag for this purpose.

Before degreasing an engine, it is necessary to prepare the engine. This can be done by using either a bristled brush or a piece of dry cloth to clean the engine bay to remove as much dust as possible.

Turn on the engine for a while

This is an important step that needs to be carried out before performing degreasing on the engine as it becomes easier to remove persistent waste like dirt, debris, and grime buildup from the engine when it is heated.

Spraying of WD40

This step involves spraying the WD40 product on the entire engine compartment, covering all nooks and crannies. It is important to wash the sprayed area with water and rinse it. 

Drying process

The engine can be left out in the open to help it dry using the sunlight. Another good way of doing so is just by keeping the car turned on to speed up the drying process or by using a table fan.

Reconnect the car battery

After the engine has completely dried off, make sure to remove the plastic coverings from the battery along with the metal and electrical components, or else the heat from the running engine can melt the plastic and cause an even greater problem.

Various uses of WD40 in a car engine

These are the various areas in which a WD40 product comes in handy.

Maintenance of spark plugs

The WD40 product comes in handy when a car faces difficulties in starting during humid or rainy weather. As WD in WD40 signifies water displacement, it can be used to remove any form of moisture or even water from in and around the spark plugs. 

They are also useful in removing any carbon deposits formed in and around the spark plugs and are useful as they prevent moisture from reaching the ignition. 

To conduct maintenance on the spark plugs, the car must be turned off and WD40 needs to be sprayed on the spark plugs to remove all moisture. The car now needs to be started to check if the remedy worked.

Cleaning car license plates

In case the car is aging and has a dirty and rusty license plate, a WD40 treatment can help restore it to its original condition. This can be done by spraying the product on the plate and letting it sit for about a minute. It can then be wiped and rinsed with soap and water for a new and clean license plate.

Loosening and cleaning nuts and bolts

Applying WD40 product on certain nuts and bolts that are stubborn and won’t come out can be loosened and cleaned as the formula has the ability to penetrate these nuts and bolts and rub against the threads, thus cleaning and loosening them.

Tackling paint scuffs

Sometimes, a car can get too close to our vehicle and cause some scrapes either on the sides or on the front, and rear bumper. These scrapes are what we refer to as paint scuffs.

Applying a WD40 product to these areas twice, and rinsing them off with soap and water afterward can do the trick. Although, it is to be noted that this trick can only work for scuffs across a smaller surface area.

Protection against winter problems

A common problem in winter is the sticking of metal surfaces, causing them to have a hindered movement. Applying a WD40 product on the doors, engine gaskets, and even the windshield wipers helps in avoiding such situations while also increasing their life.

Criteria for selecting the best engine cleaner

These are the following criteria that need to be followed to ensure we select the ideal engine cleaner.

Cleaning formula

The cleaner should not contain any toxic or environmentally hazardous chemicals that can pose a threat to both the driver and the car engine.


An ideal engine cleaner should not contain harmful vapors and should not emit any kind of odor from under the hood that can make driving difficult.

Residue Formation

The cleaner should not leave behind any kind of residue as that is another problem added on top of cleaning an engine.


The engine cleaner should be flexible so that it can be used on different kinds of surfaces instead of a particular metal or alloy part. It should also be usable on rubber and plastic-based components.

Research has shown whether WD40 can be used as a substitute for engine oil.


This blog post addressed the question, ‘Why is WD40 used in car engine ’.

We understood the various ways in which a WD40 product can be used to clean an engine and the various uses it has in the automotive field. Furthermore, some criteria for selecting the best possible engine cleaning agent have also been discussed. Please feel free to comment on the content or ask any questions in the comments section below.

Frequently Asked Questions (FAQs): Why is WD40 used in car engine?

Why would you put WD40 in your engine?

WD40 is mainly applied in an engine for its great moisture removal properties, as it can remove moisture from the spark plugs and promote proper combustion without letting the moisture reach the ignition and hindering it.

Will WD40 hurt your engine?

WD40 helps in deep-cleaning the engine and forming a protective layer over the different metal and electrical components. It does all this without causing any kind of damage to the engine as it contains rust-resistant properties that help protect the engine components.

What happens when you spray WD40 into your gas tank?

WD40 when sprayed inside the gas tank will only clean up the fuel a bit and combust along with it, thus acting as secondary car fuel.