Cleaning your car or truck motor with an engine degreaser might not be the most enjoyable job in the world, but there are plenty of good reasons for doing it. For one, a long-term buildup of grime could be causing or hiding problems; a degreased engine is easier and more pleasant to work on; and, if you’re thinking of selling your vehicle, popping the hood and seeing a nice, clean motor makes a great impression and adds value.
Degreasing the engine isn’t something you need to do very often (unless you exhibit cars), but even the best degreasers are very affordable. So, the question is, which one is right for your needs? There are hundreds of different products to choose from, and everyone claims that theirs is best!
Here at BestReviews we’ve been putting those claims to the test. We’ve checked the capabilities of dozens of different formulations so we can help you decide which one to buy.
Although engine degreasers are generally safe to use, some have a strong and unpleasant odor. Always work in a well-ventilated area.
These products can be divided into two basic types: solvent-based and water-based degreasers.
Solvent-based engine degreasers have been around for generations and are undeniably effective. The main argument against them is an environmental one: they all contain petroleum derivatives of one kind or another. Their production often involves chemicals that are toxic or harmful to people, animals, and plants. They can also be unpleasant to work with. Generally speaking, they’re deemed hazardous, and disposal can be difficult. Increasingly, their use is being restricted by organizations like the Environmental Protection Agency (EPA).
Water-based engine degreasers used to have a reputation for working more slowly and less effectively, but now most perform as well as their solvent-based counterparts. They’re usually safe to use on plastics and paintwork (though the instructions should be read carefully). It’s still important to be aware that cheap water-based products may only be suitable for light- or medium-duty cleaning. If you need heavy-duty power, you want to pay careful attention to the product description. Alsocheck what other people have to say about it. When it comes to performance, there’s nothing better than unbiased customer feedback.
Note that water-based products may be non-toxic, non-corrosive, and biodegradable, but after you’ve used them to degrease your engine or tools, the resulting liquid contains all that oil, grease, and dirt you’ve just washed off. It’s then just as likely to be considered “hazardous” as solvents, so you still need to dispose of it responsibly.
Although water-based engine degreasers may not be flammable, the propellants in spray cans often are. Assume it’s not safe to spray near naked flames or onto a hot engine and you won’t go wrong.
There can be considerable variation in how long different products take to work. Most are effective with a single treatment, but a second application may be required if there’s really heavy buildup.
Foam: Formulas that foam on contact tend to be the quickest, and some work almost immediately.
Gel: Heavy-duty versions frequently come as a wipe-on gel. It’s more aggressive, but it works more slowly. It might need to be left on for 10 minutes. In commercial situations where time is money, this can have an impact, though it’s perhaps less important for the home user. Don’t leave it on for hours and hours, though. These products need to be rinsed off to prevent any damage to surface finishes.
Smaller quantities of engine degreaser generally come in aerosol spray cans, which makes it easy to apply. If you’re going for economy and buying a gallon, it probably just comes in a big plastic container, but you can buy spray bottles very cheaply and fill as required.
Some engine degreasers are designed to be used as is, but many are supplied as a concentrate that can be diluted with water. The latter is useful because it allows you to adjust the strength for different tasks.
Check which surfaces the product is safe to use on. It’s common for water-based degreasers to be okay on plastics, paintwork, rubber, and so forth, but solvent-based products may damage these as well as finishes like chrome plating.
Although we call them engine degreasers, many of these products are much more versatile than that and can be used for all kinds of cleaning jobs from (non-food) work surfaces and flooring to decking and boat hulls. If you’ve got a tough cleaning job, one of these products could well be the best solution.
Some engine degreasers smell quite unpleasant, while others can have a fruit or floral fragrance added. It probably doesn’t make any difference to the product’s effectiveness, but some are certainly nicer to work with than others!
DID YOU KNOW?
Degreasers aren’t just for engines. They can be used to clean many different kinds of mechanisms and tools and also to clean up oil spills on your garage floor or driveway.
Eye protection: Pyramex Fortress Safety Glasses
Occasional splashes are almost inevitable when you’re using an engine degreaser, but you do not want to get that stuff in your eyes. For just a few bucks, these glasses can help prevent painful accidents. The lenses resist fogging and scratches, the nose pad is adjustable, and the arms have soft tips for added comfort.
Gloves: Adenna Nitrile Gloves
Degreasers may be great for your engine, but they’re not too kind to your hands. These rubber gloves are specifically designed for auto mechanics and other engineering uses and don’t give the allergy problems that latex products can. With 100 in a box, they work out to just a few cents each.
Absorbent mat: New Pig Super Absorbent Mat Roll
You can try using drip trays, but you never know quite where that engine is going to drip! This long-lasting mat will sop up a surprising amount of dirty liquid and retain it, making cleanup fast and easy. It comes perforated, so you can tear off just what you need.
Engine degreaser prices
You can buy small 4-ounce cans of degreaser or 15- or 16-ounce bottles that cost from $3 to $8. They’re good for tools and spot cleaning, but you’ll probably need at least a couple of bottles for a whole engine.
Larger containers of concentrate start as little as $10 a gallon, though cheap formulations might not be particularly effective on heavy buildup.
Most engine degreasers from well-known brands work out to somewhere between $25 and $40 per gallon, which is the most economical way to buy if you’re going to do the job fairly regularly.
If you’re using a water-based product that needs to be diluted, mix as recommended and then try a test patch. If it’s taking a while to work, you can always make it stronger.
- Remove the negative terminal from the battery. Do this before you start the degreasing process so there’s no current running through the electrical system. Taking the battery out isn’t necessary, though some people prefer to do so.
- Cover electrical components, distributor, ignition wires, air intakes, and carburetor (if fitted) in plastic. You can use food wrap or plastic bags. Tie a length of green garden twine or bright nylon string around each as a reminder to remove the plastic when you’re finished. You don’t want to melt plastic all over your clean engine!
- Protect the floor. Place drip trays or an absorbent mat under the engine.
- Put on protective clothing. At a minimum, wear gloves and goggles or safety glasses. Wearing an apron or coveralls is also a good idea.
- Spray or brush on the degreaser. A couple of nylon-bristle brushes of different sizes will help you work the product into all the nooks and crannies. Don’t rush. Be patient and thorough.
- Wait. Leave the product on the engine as long as specified in the instructions.
- Rinse. And pat yourself on the back for a job well done!
All engine degreasers must be kept out of reach of children and pets. The product might be advertised as nontoxic, but you don’t want your kids or animals to ingest it.
Q. Should I warm up my engine before using a degreaser?
A. It can certainly help to soften tough deposits, but you should never work on a hot engine. If you can’t touch it with the palm of your hand, it’s too hot. When we consulted detailing professionals, we found that in the past it was the practice to work on engines that were running, but that’s no longer that case, and many are happy to work on cold engines.
Q. Do degreasers damage car paintwork?
A. It very much depends on the product. With some, you should definitely avoid contact, though many modern formulations claim to be safe. As with any chemical cleaner, it’s important to read the instructions carefully. We would suggest that even with those that are safe it’s best to keep paint contact to a minimum and rinse off those areas as quickly as possible.
Q. Can I rinse used engine degreaser down the drain?
A. No. You should avoid it as much as possible. It’s illegal to pour hazardous chemicals into any part of your community’s water system. If you’re on a septic tank, it could kill the bacteria that make it work. Even if the product itself is marked as environmentally friendly or biodegradable, by the time it has gathered all the dirt and oil off your engine the resulting mixture will be unpleasant and possibly dangerous. The ideal solution is to use tough, absorbent matting like the one we recommend above, which can be reused and eventually disposed of at a hazardous waste collection center.