Shake Your PCV Valve
This sounds complex, but it’s not. 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. Some late-model cars don’t have PCV valves, so don’t beat yourself up trying to find it. 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. 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 (oem1stop.com); rates start at about $10 a day. Non-factory manuals are cheaper, but they’re skimpy on instructions and diagrams for these kinds of repairs.