Having just arrived in Paonia, Colorado for the summer, reader Ashlee thought she should get her oil changed. Not yet familiar with the area, she went with a name she recognized–Walmart. The oil change seemed to go fine so Ashlee and her friend decided to embark on a trip to Denver. Thirty minutes into the road trip, she heard a strange noise coming from the engine. She pulled over and intuitively checked the dipstick which revealed zero oil. Ashlee then looked underneath her car and saw oil covering much of the undercarriage. Eventually, she got the car to town where a mechanic discovered that the oil cap had been put on improperly, allowing the oil to escape. Later, she received an estimate from GMC of $5,875 to replace the engine. Ashlee’s letter, inside…