You should always watch for warning lights on your dash, but moreso after you've visited a "Skippy Lube".

Dear Car Talk | Feb 01, 2004
Dear Tom and Ray:
I have a nice Ford Focus, which has never given me trouble. It is my first car, so I have tried hard to take good care of it. I follow the manual, and take it to a quickie oil-change place (whose name I won't mention) every 5,000 miles. Other than trying to sell me service I don't want, it has done good work for me. Then in the faculty lounge at lunch, I heard my co-workers talking about the terrible experiences they had when getting their oil changed. Apparently, they know of people who go to the same place I go, who have had their oil drained out and then not replaced! This did not become clear to these people until the engine totally seized up and died. They said the quickie-lube place would take no responsibility, because nothing could be proven. This terrifies me! Is it only an urban legend, or does this really happen?
-- April
TOM: Oh, it absolutely happens, April. Didn't the Mars lander crash a couple of times before they got it right? And those guys were rocket scientists. You think neighborhood mechanics don't screw up sometimes?
RAY: To be fair to Skippy Lube, it's one of those mistakes that any shop can make. Although when speed is your stated priority, I suppose mistakes become a bit more likely.
TOM: Here's how it happens: The mechanic drains out the oil, changes the filter, puts the drain plug back in, takes the car down off the lift, and then his wife calls to discuss the kid's braces. Then his bookie stops by, wanting to be paid, and then the roach coach comes and it's lunchtime. If he's not careful and he doesn't have a good system, he forgets that he hasn't refilled the crankcase, and he calls you and says "all set."
RAY: You pick up the car, drive away, and 15 minutes later you're broken down by the side of the road and the buzzards are circling.
TOM: Now, normally in that situation, a decent shop will immediately take responsibility, apologize and get you a new engine. Most shops have "bonehead" insurance, which covers just these kinds of mistakes.
RAY: But I'm sure there are some sleazeballs out there who try to wriggle out of it. Why? Maybe it's pressure to increase profits (insurance has deductibles, and premiums go up with each claim). Or maybe they're just not nice people, and they think they can get away with it.
TOM: But they usually can't. If your engine seizes up due to lack of oil, and you can show that you recently had an oil change at a repair shop, almost any judge in small-claims court will award you a new engine. It's usually a slam-dunk case for the consumer.
RAY: So, keep two things in mind, April. First of all, mistakes happen, but catastrophic mistakes like this are pretty rare. And even if you are ever a victim of such a mistake, you can hold the shop responsible.
TOM: And second, remember to always pay attention to your oil light. Your oil light is an emergency warning light. If it ever comes on, pull over and shut off the engine immediately. And then check to make sure you have your latest Skippy Lube receipt. The judge will want to see it.