Engine degreasers are a varied group of cleaning agents. They each work by dissolving grease and grime, making it easier to rinse or wipe away. However, they do not all contain the same active ingredients, and they do not all work equally. The best engine degreaser is the one that cleans the whole engine compartment without damaging its surfaces.
How Does it Work?
When applied to a non-water-soluble substance like grease or oil, degreasers weaken the surface tension of the substance. The two substances then mix, and the grease takes on more of the degreaser’s consistency. When they are loosened in this way, grease and oil no longer cling to the surfaces in the engine bay and can be washed away.
Types of Degreaser
There are a couple distinct categories of engine degreaser on the market. The heavy duty type usually contains petroleum distillates or some other hydrocarbon solvent. These are harsh chemicals that necessitate protective gear – chemical gloves and goggles at a minimum. They also can create a disposal issue, as they mix with grease and migrate to the floor beneath the vehicle.
Some degreasers are created for lighter-duty applications, such as the home garage. They may use milder detergents or natural ingredients like citrus to emulsify grease and oil. These degreasers seldom work as effectively as the heavy duty ones, but they are far safer for the user and for the surfaces in the engine bay. These products are usually more akin to all-purpose cleaners than heavy duty degreasers.
For a quick rundown on how easy it is to degrease your car’s engine, check out this YouTube video of someone tackling job. He does things a bit differently than our step-by-step guide below, but there are always multiple ways to accomplish cleaning chores. The guiding principle (taking steps to do no harm to the engine) remains the same.
How to Use Engine Degreaser
Step 1 – Debris Removal
This step is the pre-cleaning cleaning. Before you do anything else, look around the engine compartment and remove any loose debris you find. Look for leaves, acorns, twigs, insects, etc. Look closely around the firewall and the scuttle drains (the gutters beneath the windshield). You will need water to flow during the rinsing process when you clean the engine, so leave no debris behind.
Step 2 – Protect Electrical Components
Regardless of how old or new your car is, you will need to take some time to protect its vital components. First remove the battery to prevent electrical shorts. This also keeps you from having to protect the battery during the cleaning process. Older vehicles will have a distributor that needs covering.
Newer cars may have coils atop each cylinder. These need protecting as well. Look for any other electrical connectors and cover them, but don’t bother with coated wires. Don’t forget the alternator. I like to wrap plastic storage bags or grocery bags around components, taped tightly to the wiring. Aluminum foil works well too. Take your time with this step and be thorough.
Step 3 – Warm the Engine
Make sure you are parked in a well ventilated area. Start the engine and let it run for a few minutes to warm up. Most engine degreasers work better on a warm engine. This process heats any built-up grease, liquifying it to some extent and making it easier to remove. Be careful not to apply cold water to a hot engine, however, as that can (rarely) lead to serious problems like cracking metal components.
Step 4 – Apply the Degreaser
Most engine degreasers require a smooth, even spraying over all surfaces of the engine. Read the directions carefully to ensure that the product you selected is suited for your engine. When in doubt, test a small amount of the product on the surface in question in a nonvisible location. If it doesn’t stain it or react, you should be good to go.
Step 5 – Let the Product Work
If the engine wasn’t very dirty, allowing the product to sit for five minutes before rinsing should suffice. A particularly dirty engine may require scrubbing with a nylon-bristled brush. Whatever you do, don’t let the product dry on the surface. Most engine degreaser damage is caused this way.
Step 6 – Rinse
Use a garden hose and clean, fresh water to lightly rinse the degreaser off the engine. Use dish detergent and water to remove any stubborn degreaser. Allow the engine to air dry with the hood up before removing the bags you placed over the components, then drive the vehicle to complete the drying process.
The Best Engine Degreasers
1. Chemical Guys – Signature Series Orange Degreaser
The Signature Series Orange Degreaser is Chemical Brothers’ answer to the overuse of harsh chemicals. It is infused with citrus extracts, which do a fine job of cutting grease on their own. The addition of surfactants helps to break the surface tension of whatever grime it contacts, breaking its hold on engine surfaces.
Orange Degreaser’s other advantage is in its versatility. When used full strength, it is the mildest degreaser that can still tackle a greasy engine bay. However, it can be diluted up to 20:1 ratio. This is one of the best engine degreaser products for just about any oily mess on or around a vehicle. It will clean leaky suspension parts, steering components, wheels, tires and even floors.
- Can be used full strength or diluted 20:1
- Works well for many jobs, not just engines
- Tough on grease yet gentle on most surfaces
- Pleasant citrus aroma
- Available in different sizes
- Even at full strength, it isn’t as strong as many chemical degreasers
- Some users report discolored aluminum parts
Chemical Guys makes detailing products that professionals trust. The Signature Series is a common item in mechanics’ home garages because of its versatility. As an engine degreaser, it is a bit underwhelming. But it frees up space in the chemical cabinet.
2. Meguiar’s – Super Degreaser
Despite the lack of thought that Meguiar’s put into the name, Super Degreaser is a an effective product. It is concentrated, and it will do a good job of emulsifying light oil deposits around engines, but it struggles with baked on grime. Diluted, Super Degreaser also makes a fine detailing solution for non-painted surfaces.
Super Degreaser fits neatly into the product category for customers who don’t want to use overly harsh chemicals to clean their engines. Stronger chemicals are more inclined to damage parts or paint. Then again, they also require less elbow grease. Super Degreaser requires either more work or more applications to accomplish what harsher chemicals can do by themselves. But then you have to live with them.
- A milder chemical degreaser than many competitors
- Can be diluted to work on more surfaces
- Gently cleans oil stains on concrete
- Clean, non-offensive scent
- Can even clean leather interior
- Not the strongest available degreaser
- Requires more work on the part of the user than many others
Meguiar’s makes more car detailing products than anyone could memorize, but it has a few gems on its hands. For the detailer who is petrified of causing damage to engine surfaces, it is one of the mildest possible options. It won’t self-clean like a foaming degreaser might, but it leaves no trace of having been used. Multiple uses is a fringe benefit.
3. Shaeffer’s – Citrol
Citrol is a non-toxic degreaser that is suitable for use even in food plants. It also happens to be extremely effective at emulsifying the grease and oil that accumulates under the hood of a vehicle. This citrus-based product is biodegradable and environmentally friendly, making it a favorite among home mechanics.
The organic citrus ingredient in Citrol is mixed with a non-petroleum surfactant-emulsifier solution. It works well for cleaning engine bays as well as suspension and steering components. It is also safe enough to use on any household surface, though not those that come into direct contact with food.
- Contains no harsh chemicals
- Relies on the cutting power of citrus
- Spray can for convenience and storage
- Aroma is bright and lingers after use
- Useful on any greasy surface, not just for cars
- A bit more costly than some concentrated formulas
- Cannot be diluted
Schaeffer’s products are not known for being cheap, but they outlast their competition, so the savings is in longevity. Citron makes short work of cooked-on grease and oil under the hood, and works well around the house. It is one of the safest degreasers to use around kids or pets.
4. S100 - Total Cycle Cleaner
Don’t let the name fool you, this product isn’t just for bikes. Total Cycle Cleaner is the best engine degreaser aluminum component owners can use. The crew at S100 designed Total Cycle Cleaner as a spray-on, rinse-off motorcycle cleaner. It emulsifies all types of road grime, oil, chain wax and grease on contact. Simply dilute it in a spray bottle like in this YouTube video and spray it into all those hard-to-reach places.
The PH-balanced formula is biodegradable, yet it contains anti-corrosive agents for long lasting protection. It has been cleaning bikes since 1985, with a proven track record of being safe for polished aluminum, chrome, paint and powder coating. If your car is your baby, Total Cycle Cleaner can keep it looking like it did in the showroom.
- PH-balanced with no harsh chemicals
- Biodegradable for guilt-free use
- Requires no scrubbing
- Four decades of proven performance
- Safe on aluminum, paint, chrome and other easily marked surfaces
- Not the cheapest degreaser available
- Container difficult to pour from without spilling
S100 makes quality car care products, but they don’t come cheap. That said, they are not overpriced either. Total Cycle Cleaner does its job and does it fast. How much is the time it will save you worth, not to mention the peace of mind knowing you will not harm delicate surfaces?
5. 3D – Grand Slam Heavy Duty Degreaser
When most people think of a chemical degreaser, a product like Grand Slam is what comes to mind. This product from detailing company 3D contains caustic sodium hydroxide, alkaline sodium metasilicate, and the nonionic surfactant alcohol ethoxylate. Another ingredient (EDTA) helps the mixture bind to oil and grime so it can be dissolved.
The chemical nature of Grand Slam means extra precautions must be taken with its use. It will likely discolor any paint it contacts, and it may do the same to polished surfaces under the hood. The stuff works the old fashioned way: eating away the accumulated grime. It may be the best heavy duty engine degreaser in its price range, though it is definitely not the most eco-friendly one.
- Works better than any eco-friendly competitor
- Able to be diluted for a broader range of uses
- Safe on metal, plastic and rubber components
- A proven track record of effectiveness
- Serious product for heavily caked-on grime
- Caustic – must be washed off if contacts skin
- Will stain polished and some painted surfaces – test first
The 3D brand is recognized for its effective product line. Grand Slam is no joke. It is a modern version of your grandfather’s engine degreaser – the type of product that would put hair on your chest, if it were safe to have it there. Honestly, nothing is more effective, but many contain less chemicals. Best for use on neglected engines.
The best engine degreaser is the one that does its job without asking too much of the user. Some products work too well, taking removing paint and shine along with grime. Others ask you to scrub with a brush, so your sweat supplements their lack of effectiveness. But S100’s Total Cycle Care is different. It emulsifies oil and grease effectively without coaxing, and it is safe on any surface. It is also non-toxic and environmentally friendly, so you can use it and still sleep at night.