A clean engine compartment gives a used car a newer and better-maintained appearance. Some workshops that perform engine cleaning services claim that a clean engine even runs slightly cooler, as removing dirt buildup from grime, oil, and grease allows engines to run cooler.
Apart from appearances, does a clean car engine that shines like new perform better than an engine dirty from normal use? Do you absolutely need to remove debris or use a degreaser to keep your car in good working condition? Probably not.
While it’s true that oily and greasy dirt buildup on an engine can trap heat, it’s unlikely to be enough to cause overheating or even make an engine run hotter than normal. If a car’s engine overheats, the probable cause is more likely in the cooling system—or because the car is towing or carrying too much weight, or some other issue unrelated to the cleanliness of the engine compartment. There is no evidence to suggest that a cleaner engine performs better than a dirty one. It’s unlikely that something as simple as a small cleaner or cleaning spray could improve a vehicle’s operation.
A Cleaner Engine Offers Some Benefits
However, cleaning your car’s engine does offer some benefits. First, it helps determine where oil or grease is coming from—such as a leaking valve cover gasket—so a minor issue like a small oil leak can be isolated and repaired before it becomes a major problem. Additionally, since oil and grease can accelerate the wear of rubber hoses and plastic parts, using a degreaser to clean off grime can save on repairs. And if you’re the type who likes to perform minor maintenance, like checking oil levels or accessory belts, a clean engine means your hands and clothes are less likely to get dirty.
Many mechanics and detailing workshops recommend using a degreaser and tools such as a vacuum with a small nozzle, compressed air, or a toothbrush to reach hard-to-access areas. These are preferable to blasting an engine with a high-pressure hose or steam cleaning an engine, as water and moisture can damage electrical connections and parts. Even a light spray of water in the wrong place can cause serious problems. Engine detailing requires precision and a gentle touch; trying to tackle this project at a car wash or with water from your garden hose could be a disaster.
The aesthetic appeal of a clean engine will likely be the biggest return on investment. Most used cars are thoroughly detailed before being put up for sale, including many sold by private owners, so buyers expect to see a clean engine when purchasing. A dirty engine on a used car will harm its appeal.