Dear Car Talk:
I recently checked my oil and discovered how filthy my engine compartment is. Should the engine compartment be cleaned regularly? Is this something I can do, or does it need to be done by a pro?
— Tom
There’s dirty and then there’s filthy, Tom.
I’ll stipulate that I wouldn’t want to eat off of even the cleanest engine that comes into our shop. But there’s a difference between road dirt, dust and grime, and an engine that’s been leaking oil.
An oil leak is what makes an engine compartment absolutely filthy. Not only is the used oil itself nearly black in color, but once there’s oil on and around the engine, all kinds of other dirt and grime adheres to the oil and makes the engine compartment — what’s the phrase I’m looking for? Oh, yeah — absolutely disgusting.
So, if you can wipe your finger on the dirtiest parts of the engine and pick up actual oil, that’s a job for your mechanic, not your dry cleaner.
Not every oil leak is a mechanical and financial disaster, Tom. Sometimes an easy-to-replace gasket goes bad or some bolts need to be tightened. So don’t be afraid to ask your mechanic to figure out what’s leaking.
If he finds a leak and fixes it, then you can have your engine compartment cleaned. Not so much for aesthetic purposes, but so you can tell if the oil leak is fixed and spot another one easily in the future.
There’s no real mechanical reason for an engine compartment to be cleaned, other than to make diagnosis of leaks easier. It’s something you can do yourself, Tom. There are products you can spray on the engine that foam up and then you hose it off along with at least some of the engine crud. The problem is that all that grease and oil will then run down your driveway and into your local water supply. So DIYers should find a self-service car wash that has a grease trap to capture that hazardous waste.
Professional engine cleaners will have those grease traps. And the other advantage of going to a pro is that if he accidentally steam cleans the inside of one of your car’s expensive computers and the car won’t run when he’s done, that’s on him, not you.
