The 9 Best Engine Bay Cleaners & Degreasers

When it comes to car maintenance, engine bays are often criminally overlooked, with many preferring to prioritize their car’s exterior. Keeping your car’s engine bay in good shape can have all sorts of benefits, leaving many to wonder what the best engine bay cleaners on the market are.

The 9 best engine bay cleaners and degreasers are:

  1. Bilt Hamber Surfex HD
  2. WD-40 Specialist Machine and Engine Degreaser
  3. Mckee’s Engine Degreaser Cleaner
  4. Autoglym Engine & Machine Cleaner
  5. STP Engine Degreaser Professional Series
  6. Gunk 5L Degreaser Brush-on
  7. Chemical Guys Signature Series Orange Degreaser
  8. Gunk Original Engine Degreaser
  9. Griots Garage Engine Cleaner

There are plenty of engine bay cleaners out there, offering different formulas, different levels of strength, and different application methods. In this article we’ll discuss the importance of cleaning your engine bay, as well as going through the best cleaners and degreasers currently available.

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Why Is It Important To Clean Your Engine Bay?

Engine bays seldom receive the levels of love and care that car exteriors do, which is to an extent understandable, as they are rarely on show. While the engine bay may not take center-stage as you polish your car’s paintwork, it is important not to neglect it, as a dirty engine bay can have negative effects on your car’s performance and overall condition.

Performance Benefits

The more you drive your car, the more dirt and debris it will pick up. Oil, grease and other foreign matter such as leaves and mud can block up passages in the engine, restricting airflow, potentially causing the engine to overheat. Leaving grease and dirt to build up inside the engine bay can cause parts like the alternator and various belts within the engine to deteriorate.

This will not only prove dangerous but will also cost a lot of money to get repaired, which is not what anybody wants, considering it is completely avoidable. Having a clean engine bay will reduce the risk of engine failure, as well as making it easier to perform maintenance on the engine and other parts of the car’s interior workings.

Simplified Maintenance

A clean engine bay will result in increased visibility, making it easier to spot flaws and defects with the engine. This will make it easier to diagnose any problems, as well as perform the required operation to solve the issue. It is a lot easier to locate the source of an issue such as a gasket leak or electrical fault when the engine bay is clean and grease-free.

This will also bring with it the benefit of having peace of mind. You won’t have to worry about your engine being clogged up or damaged by debris. Once the engine bay is fully cleaned, it will make routine touch-ups a lot quicker and a lot easier too. Keeping on top of a clean engine bay is easier than trying to salvage an engine bay caked in grease and dirt.

Maintaining Your Car’s Value

If your engine bay is kept in good condition, it bodes well when it comes to eventually selling your car. It shows that you have taken good care of the vehicle as well as ensuring the car will have extra longevity. Hidden parts such as the engine bay or the exhaust system can often make or break a deal depending on their condition, as well as helping to justify selling it for a higher price.

What To Look For In An Engine Bay Cleaner

Degreaser Formula & Concentration

Each engine bay cleaner and degreaser will claim that the formula they have used will work the best on hard to clean surfaces. The truth is, there is no ‘perfect’ formula, with water-based solutions usually working just as efficiently as stronger, petroleum-based solutions. Water-based cleaners require less preparation, as they won’t do as much damage if spilled as other products.

Petroleum or solvent-based solutions will often be more concentrated and tougher on ageing stains, but you will need to make sure you protect the surrounding areas of the car such as the paintwork or non-metallic components. Citrus-based formulas are usually known for their acidic quality and pleasant smell.

It is worth checking to label to see the concentration levels of the product you choose, and whether you need to dilute the solution before application. It is also important to remember to wear protective gloves and eyewear, as highly concentrated substances can cause major irritation if they touch your skin.

Application Type

There are multiple methods of application with engine bay cleaners and degreasers. The most common form is the spray bottle, which is simplistic and requires less time and effort than a brush-on degreaser would. Brush-on degreasers do allow for more accurate application, as you can pinpoint the exact place where you want to spread the cleaner.

Foam cleaners work in a similar way to spray bottle cleaners, as you spray it on to the part that you want to clean, leave it for a while, and then rinse/wipe it off. Some cleaners require brushes and wipes to agitate the grease and dirt, loosening it from its place before wiping off. Some cleaners come with detachable nozzles for more accurate application.

Value For Money

A lot of the degreasers and cleaners on the list below come in multiple sizes, with the option to purchase either a smaller bottle or a large multi-liter tub. While the individual bottles inevitably cost less, it usually works out cheaper in the long-term to buy the item in larger quantities. This also comes down to how much you can afford to spend on your engine bay cleaner.

While it will always be tempting to buy the cheapest option, it is not always the best thing to do. Cheap products may not work as efficiently as more expensive products and can sometimes cause do more harm than good to the inside of your car. It is important to check the authenticity of the brand as well as customer reviews of the product.


Some cleaners and degreasers may be designed for other uses, such as cleaning other parts of the car or other machinery. Some may prefer this as you can get more value for your money. However, others may prefer to have a specialist cleaning product that has been designed to do a specific job.

The 9 Best Engine Bay Cleaners & Degreasers

1. Bilt Hamber Surfex HD

Formula: Water-based

The Bilt Hamber Surfex HD is an ideal water-based all-purpose cleaner that can be used at varying levels of concentration. Available in a sizeable 5-liter tub, the fact that this degreaser works well when diluted with water means that you get a substantial amount for your cash. The cleaner isn’t cheap, but in the long run, this product offers great value for money.

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The cleaner itself is fully biodegradable, and will easily remove stubborn grease and stains, adding some sparkle back into your engine bay. Its all-purpose nature means you can also use it to clean other aspects of your car, such as the interior carpets, wheels and bodywork. As well as the larger five-liter option, the Surfex HD cleaner also comes in a smaller spray bottle.

The cleaner comes with dilution guidelines, which recommends the ratio of water to cleaner that you should use for various cleaning operations. As an all-rounder, the Bilt Hamber Surfex HD is one of the best cleaning products on the market.


  • Biodegradable and water-based
  • Can be diluted with water
  • Strong enough to remove stubborn grease


  • Value for money not as good when bought in smaller quantities

2. WD-40 Specialist Machine And Engine Degreaser

Formula: Water-based foam

WD-40 are a brand known for making products that work with an almost miraculous effect. This product is slightly different to most of the others on this list as it is a water-based foam rather than a liquid. The foam will penetrate into deep, hard to clean crevices, and the bottle comes with a small nozzle for precise application.

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Water-based substances won’t damage other parts of the engine area, so you won’t have to take special precautions when applying the foam like you would with other petroleum-based or solvent-based degreasers. The fact that this product is water-based doesn’t mean that it is weaker than its competition, and it will do away with grease with limited scrubbing if applied correctly.

This degreaser isn’t limited to the engine bay despite what it says on the tin, as it will do a consistent job on other parts of the car such as the exhaust tips. The foam produces a strong enough burst so it can be sprayed from up to 5 ft/60 in.


  • Penetrates small, deep crevices
  • Water-based, won’t damage nonmetallic components
  • Comes with a small nozzle for accurate application


  • Not available in large bottles

3. Mckee’s Engine Degreaser Cleaner

Formula: Non-toxic, biodegradable

Mckee’s engine degreaser will have your engine bay looking instantly cleaner, with its ability to easily break through tough grime and grease. The formula for the degreaser is based on technology used to clear up oil spills in the ocean, because of its ability to break up the molecules in the oil. This technology works the same way on your engine, immediately loosening hard to shift grease.

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This degreaser is made from a non-toxic, biodegradable formula that won’t emit any harsh fumes, as the company have steered away from using acidic ingredients when producing the product. Be sure to only use the degreaser on parts that can handle being exposed to liquid. It is also important that you don’t leave the degreaser on polished aluminum for too long, as it may stain.

The degreaser comes in two sizes: a smaller 650 ml spray bottle, which is useful for a quick fix, and a more expensive 3.78 L bottle, which is slightly better value for money. Mckee’s engine degreaser is more expensive than a lot of its competitors, but the extra money that it costs is justified by its effectiveness and the immediacy of its results.


  • Works immediately for instant results
  • Won’t emit harsh, toxic fumes
  • Capable of eliminating the toughest stains


  • More expensive than a lot of the competition
  • Can damage materials such as aluminum

4. Autoglym Engine & Machine Cleaner

Formula: Water-based

The Autoglym engine cleaner is another water-based product, which quickly dissolves oil and grease, leaving your engine bay looking immaculate. It is easy to use, as it comes in a spray bottle and only requires a brush to agitate the stains, and some water to rinse everything off after use. The degreaser is biodegradable too, meaning you’ll be doing no harm to the planet when using the product.

As with most of the products on this list, it is important that you cover the more vulnerable components of the engine bay before you use the cleaner. It’s advised that you don’t let the product dry before you rinse it off, otherwise you won’t be extracting the cleaner’s full potential. This cleaner isn’t as effective as others at instantly removing grime, but for a low price it is a solid option.


  • A cheaper option
  • Biodegradable and water-based
  • Easy to use spray bottle


  • Won’t work as quickly as other products
  • The spray trigger can sometimes be slow to return to normal state

5. STP Engine Degreaser Professional Series

Formula: Petroleum-based

This heavy-duty engine degreaser is designed to rid your engine bay of the toughest grease stains. It is a powerful, corrosive, petroleum-based product, which will most likely cause damage to paintwork and other aspects of your car if used inappropriately. However, it works perfectly on metal surfaces, especially ones that haven’t had a decent clean in a long time.

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The formula is designed to penetrate and dissolve oil and grease, breaking them down to the point where you can wipe them away with ease. While the strength of this degreaser is no doubt its strong point, it can cause major irritation if it comes into contact with your skin or eyes, requiring precautions to be taken before use. Always wear gloves and eye protection when using this product.

As it isn’t water-based or biodegradable, it is advised that you lay down some floor protection underneath your car, as you will be at risk of staining should the residue spill onto the floor. For a low price, this cleaner from STP certainly packs a punch, and will eradicate tougher stains with ease.


  • Strong and effective in removing tough grease
  • Cheap
  • Easy to use


  • Can cause damage to surfaces
  • Potentially hazardous without gloves or eye protection
  • Non-biodegradable

6. Gunk 5L Degreaser Brush-On

Formula: Solvent-based

Gunk have become a reputable brand in the degreaser industry over their 50+ years in the business. Their solvent-based brush-on product comes in a 5-liter tin, meaning it looks the part as well as doing a fine job in ridding your engine bay of grease. It is a brush-on cleaner rather than the usual liquid spray, but it’s thin enough to decant into a spray bottle should you prefer that method.

The Gunk degreaser is more suited to deep cleans and large jobs rather than quick touch-ups, and as usual, it is recommended that you cover up the more sensitive parts of the engine bay before application. Protective clothing is also essential as this degreaser is solvent-based and can cause irritation if it makes contact with your skin.

Brushing on degreaser is a very satisfying experience, and with the power of this Gunk product, you will see fast results. One issue you may experience is a dull white film forming after the product has been used. The degreaser will need to be rinsed thoroughly and wiped off after use.


  • Trusted, reputable brand
  • Can clean large areas effectively
  • Fast results


  • May leave a white film after use
  • Hazardous if touched or ingested

7. Chemical Guys Signature Series Orange Degreaser

Formula: Citrus-based

The Signature Series Degreaser by Chemical Guys is the first citrus-based product on this list, and it has had its powers bolstered by the addition of hyper surfactants, detergents that increase the spreading and wetting properties of the degreaser. The Orange Degreaser will easily cut through tough grease and oil and separate it from the surface of the engine bay.

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Having the dirt separated from the engine bay’s surface means that it will be removable with a simple wipe, rather than requiring any laborious scrubbing. The cleaner can be diluted and used for other purposes, such as garage floors or external parts of the car. The degreaser is reasonably priced and can be purchased as either a 473 ml spray bottle or a 3.78 L tub.


  • Separates the grease from surfaces very well
  • Versatile, all-round useability
  • Pleasant smell


  • Can leave streaks if not rinsed correctly

8. Gunk Original Engine Degreaser

Formula: Foam-based

The Gunk Original Engine Degreaser is a highly concentrated degreaser that comes in an aerosol can for ease of use. It is a very fast working degreaser, which can be rinsed off with water around 15 minutes after the initial application. Due to its high concentration, this degreaser works best on engine bays that have seen better days, as it will break through even the toughest stains.

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It features a foam-based formula, which will dissolve itself into the surface of the engine and the engine bay, while fighting off the stubborn dirt that has amassed over long periods of time.

Gunk has been a mainstay in garages for over half a century, meaning the company must be doing something right! Even though their Original Engine Degreaser isn’t the most versatile, it will do the job that it is advertised to do with great competence.


  • Takes minimal time to work
  • Can cut through old, stubborn grease
  • Reputable company


  • Not versatile
  • More expensive than some competition

9. Griots Garage Engine Cleaner

Formula: Mild degreaser | Size: 651 ml / 3.78 L (22 oz / 128 oz)

The Griots Garage Engine Cleaner is made from a milder formula than most of the other products on this list, which means it won’t corrode the surface of the engine bay after frequent use. The cleaner is manufactured, bottled, and sold independently from the company’s US headquarters.

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It comes in a spray bottle or a larger tub, and it will require you to do a little more scrubbing and rinsing due to the lower concentration. It is designed for those who enjoy taking time and putting a lot of effort into caring for their vehicle. Unlike the Gunk product above, this cleaner works best for cars that haven’t been exposed to a heavy build-up of hard to remove, ageing grease.

You don’t have to be as careful to protect other areas of the car from this liquid as it won’t do as much damage to other non-metallic materials and the car’s paintwork as some of the other more concentrated options. However, it is still important to cover the parts of the engine area that shouldn’t be exposed to liquid or chemical products.


  • Won’t corrode parts of the engine bay
  • Sold in two sizes
  • Won’t damage car paintwork


  • Takes more effort to use effectively
  • Will struggle to remove the toughest stains

8 Steps To Clean Your Car’s Engine Bay

1. Let Your Engine Cool

The first step is to let your engine cool down. Cleaning an engine while it is still hot can put added stress on the metals inside, potentially causing them to crack. This will allow water to get inside, which can lead to a whole host of other problems. You can still clean the engine on a hot day, but just avoid cleaning it straight after you have driven the car.

2. Remove The Negative Battery Cable

The next step is to remove your engine’s negative battery cable. Doing this will protect the car’s electrical components from water damage. You can take the entire battery out if you wish, but it is possible to thoroughly clean the engine bay while it is still in there. Make sure you remove the negative cable before the positive one to avoid an electric shock.

Note: Make sure you know what you’re doing before removing your car’s battery, as it can be a dangerous job if not done properly!

3. Cover Vulnerable Parts

It’s important that you cover up all the sensitive electrical parts that shouldn’t be exposed to water or corrosive cleaning substances. This will ensure you don’t do damage to vital parts of the engine, as well as giving you the peace of mind that you can do a thorough job without worrying about damaging anything.

4. Brush Off Any Surface Dirt

Before you really delve into the engine with cleaners and degreasers, get rid of any removable surface dirt with a wipe, as it will be one less thing for your cleaning products to have to penetrate. Remove any leaves that may have become trapped in the engine bay, and anything that can be removed without scrubbing.

5. Apply Your Cleaner/Degreaser

Apply your cleaner or degreaser to the entire engine bay, ensuring it can get into the harder to reach areas. When you have done this, scrub the solution with a brush to agitate the stubborn dirt. Leave the solution to set, but don’t allow it to dry completely. If you have used a strong degreaser, you may not need to scrub. Make sure you cover every possible area in degreaser.

6. Rinse

After you have left the degreaser solution to set in and do its work, rinse off the engine bay with either a light spraying hose or a wet cloth. You may find it easier to use a cloth as it is easier to avoid getting the electrical components wet. If there is still dirt on the engine bay, repeat the process, but home in on the specific area where the mess still exists.

7. Dry The Engine Bay Off

After you have rinsed off the dirt, dry the engine bay with a cloth or towel, making sure you can reach every area that has excess moisture. If you are cleaning your engine outside on a warm day, this job will be made easier by the ambient temperatures.

8. Maintain The Engine Bay

If you make sure to repeat this process every so often, it will become easier and easier to keep on top of, compared to if you do it once every few years. Engine bays will keep picking up dirt, oil, and other degrading substances for as long as you drive the car, so it really helps to keep tabs on the state of the engine bay.

Final Thoughts

When it comes to finding the right engine bay cleaner and degreaser, the best choice is the Bilt Hamber Surfex HD, thanks to its high strength and excellent degreasing properties. Cleaning and maintaining the engine bay is a job that should never be overlooked, due to its importance in keeping the engine running efficiently.

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