I have 2 plugs that are wet, black, and oily. The rest are perfectly chocolate brown. Car runs great, no smoke anytime. But, I'd like to check my rings (compression). What is the cheapest (and still accurate) method? Advance Auto, Napa, or Autozone have something for sale?

 

Any autoparts store should have a compression tester either for sale or rent, you can pick them up fairly cheap just to have one in the toolbox...


If you do find low compression in the cylinders try squirting a bit of oil down that cylinder. If the compression jumps up you have a ring problem, if it stays the same you have a valve not seating or possibly both.