Took my wife's Mazda with ~8,000 miles on it (barely broken in) into a Grease Monkey in Pueblo West once to get a quick oil change before we took a road trip. The young mechanic came out after about 20 minutes with a very somber look on his face and fresh printed sheet of paper with lots of charts and graphs on it, and sat down next to me like a dr. in the hospital does when delivering bad news...he had had some concerns and, without asking permission but as a totally complimentary service, tested the engine compression for me! He pointed at various pictures on his little paper that showed my compression was at least 30% below spec and used many complicated-sounding terms that probably worked great on the little old ladies that bring their cars in, so I interrupted him to ask if the engine was running soooo badly HOW ON GOD'S GREEN EARTH HAD I MANAGED TO DRIVE IT TO THEIR SHOP THAT DAY?! Of course he had no answer for that, and I asked him very politely to take his rear end back to the bay and finish my oil change while I stood there and watched. That was the last time I went to a quick-stop place...Oh, we put another 50K on that car and sold it to my brother who has added more then that, the compression is still fine.