First of all a chiltons or haynes manual for your vehicle is worth it's weight in gold. You can fix most problems with a little elbow grease and a few tools if you have one of those. Youtube is also very helpful for this.
Second, years ago before we met my "wife" took her eclipse to walmart for an oil change. Well the engine seized about a mile down the road because the forgot to refill it. They wouldn't pay for the damage either since she signed the forms saying that their work was ok. Ended up totaling the car since the engine needed to be replaced after that.