Shake your PCV valve

If your car has a PCV valve

(some late-model cars don’t), pull it out every other oil change. In most cases, you’ll find the valve on the top of the engine, connected to a vacuum hose. Slide the vacuum hose off the valve and unscrew the valve. Then perform the world’s easiest diagnostic test: Shake it. If it makes a metallic clicking sound, it’s good. If it doesn’t make noise or sounds mushy, replace it ($4). But don’t replace it on appearance alone—all used PCV valves look dirty.

Need help locating your PCV valve? Buy a short subscription to an online factory service manual, which you can get at sites such as eautorepair.net and oem1stop.com. Non-factory manuals are cheaper, but they’re skimpy on instructions and diagrams for repairs like this.