It happens at the worst time - stuck in traffic or a long road trip - when you see that check engine light flick on. Here's why it may keep returning.

At a time when vehicle diagnostics can demand a computer science degree, being able to get some insight into your engine health with nothing but a rag and a bit of know-how can be downright refreshing ...

It sounds like a basic procedure — pull the dipstick, check the oil level, and top off if needed. However, if that is your whole game plan, you might be missing what the dots and lines on that metal ...