If you've ever cleaned a slightly neglected oven tray you'll quickly learn how much of a pain in the neck grease can be to clean, especially if you're using water.
The same is true for your car's engine bays. They get incredibly dirty over time, with muck and road grime being constantly thrown into the engine bay while deposits of oil and grease build up too. And while most other surfaces can simply be blasted with a pressure washer, it's not a good idea to fire 100 bar directly at your alternator or distributor.
This is why a good degreaser makes so much sense. Simply spray it onto your engine, agitate it with a brush for a few minutes and wash off with some water (be careful with that mind). We've researched and found the best examples currently for sale and some useful information so your engine bay can sparkle.
The best degreaser
Bilt Hamber Surfex HD Cleaner
The best degreaser and APC
A combination of degreaser and all-purpose cleaner (APC), Bilt Hamber Surfex-HD Cleaner is our number one pick for decreasing your car. Water-based and fully biodegradable this degreaser is effective in oil, grease and organic deposits that build up in your engine bay. It's also very good value for money and can be diluted to clean paintwork, carpets, wheels and tyres.
Autoglym Engine & Machine Cleaner
The best degreaser and detergent
An effective spray-on engine cleaner, Autoglym's water-based Engine And Machine Cleaner is a fantastic choice for removing oil, grease, grime and traffic film. Working as both a degreaser and a detergent it's incredibly easy to apply and will clean your engine bay very effectively. It misses out on the top spot for the simple reason that Bilt Hamber's offering is better value for money.
STP GST73500ENP Engine Degreaser Professional Series 500 ml
The best degreaser for really mucky surfaces
The big guns of degreasing, this heavy-duty engine degreaser will penetrate and dissolve dirt and deposits. The spray should be applied to a warm engine, allowed to sit for 10-15 minutes before being washed away with water. It's a petroleum solvent however so be careful of getting it onto rubber parts and paintwork.
Granville Gunk 734 5L Degreaser
The best bulk degreaser
Offering a more than generous five litres of degreaser, this solvent-based degreaser is good for degreasing an engine so long as you're careful about not spilling it on paintwork or any asphalt. It's an effective choice but does leave a rather annoying film as you wash it away.
WD-40 Specialist Fast Acting Degreaser
The best degreaser for small areas
This solvent-based degreaser comes with WD-40's excellent 'Smart Straw' which makes it a great way of removing grime and dirt in small areas, like screw heads for example. It's good at penetrating oil, dirt and grime in as little as a few minutes. Safe to use on metal and glass, it's perfect for small jobs (including around the home) but any larger task will quickly prove that the 500ml aerosol is not large enough.
Meguiar's G180224EU Heavy Duty Multi-Purpose Cleaner
The best degreaser for general use
Not as powerful as the other options here, this degreaser can be used on more surfaces. Safe for use on metal, rubber (including tyres), plastics and fabrics, it'll help remove grease, grime and dirt with a couple of squirts from the bottle.
You'll probably want some brushes for your engine bay too:
What you need to know about degreaser:
How does degreaser work?
Dust out the GCSE chemistry books - degreasers have everything to do with hydrophobics. Old and grease are hydrophobic and as such degreasers make use of both hydrophobic and hydrophilic molecular chains that dislodge the oil.
Why should I care about a mucky engine bay?
Not only will it look a lot nicer if your engine bay is looking clean, but it can also help you spot any issues that may be developing quicker. A split in your exhaust manifold or perished rubber, for example, will be a lot easier to spot and catch if your engine bay is clean.
Not to mention that when it comes to sale time, a clean engine will undoubtedly net you a few extra quid.
What should I look for in a good degreaser?
The most important consideration to make with degreaser depends on where you plan on using it. If you're wanting to clean your engine bay look for a water-based option if possible. Solvent-based degreasers can break down rubber and vinyl which could potentially spell disaster for your engine.
Water-based degreasers are also better for the environment. Several of the degreasers we've selected are biodegradable too, a far cry from the kerosene-based degreasers of old.