My wife and took our Durango to a jiffy Lube for a basic oil change. When they were finished they took us out to our car and showed us that all the caps where tight and checked the oil level. There was no oil on the dipstick. My first thought was that they had just under filled it since it takes 7 quarts. She called the manager over who checked it. The manger asked the “lower bay technician” to pull the plug to see if there was any oil in it. There was but it came out very slow and was dirty. The manager then added 3 quarts and rechecked…no reading. She added 1 quart…no reading, 1more quart no reading and then 2 more quarts and it finally read full. I used to work at a jiffy lube many years ago and I know how their procedures work, so when she told me sorry for the inconvenience but “everything is good to go” I said…“We have a problem”. I know that once they top off the oil they start the car to check for oil pressure, this means the engine was running without oil for 10-30 seconds. I explained this to her and after several minutes she admitted that they had run the engine without oil but everything would be fine and to call her if there was a problem. I demanded and a letter from her (on the spot) that stated that they ran the engine without oil. She hesitantly complied and wrote a quick letter. My main question is: did it damaged the engine and will it show up right away? What action should I take?