Star GMC Quakertown

Worst experience ever!!! I bought a 2013 GMC Terrain with about 20k miles. My first oil change at about 26k miles I found my car was 2 quarts low on oil. Then before my next oil change my engine was knocking. Because of my horrible experience buying the car at Star Gmc I took it to another GMC dealer for consumption tests which took another 8k miles to do the tests. During which I tried to trade my car into Star for a Subaru Outback and explained my whole situation with the oil. I was ready to sign papers but they said the were going to give me $16k for a car I bought for $22k 8 months prior. I obviously left upset and let them knowing that I was not happy. I finished my oil consumption tests and the other dealer said General Motors allows a loss of 1qt for every 2k miles. They say that you should check your oil every time you fill up with gas. It says it in your manual. Crazy right? I called Star and talked tof the sales manager and he said he will work with me but that I am looking at that large of a loss because they have to look the car over, the car was older at that point with more miles and they changed how they look so that depreciated the value. He also said we all lose whenever we buy a vehicle and trade it in, even him. At his request, I text him vehicles I like that they had to see how they could help me out. He said he would let me know. He didn't get back to me so I called him again and he said he would get back to me. He never did. I took my business elsewhere and bought a Dodge. I posted a review of my experience and got a reply from the owner online and a call from that same sales manager. First he tried arguing saying I didn't try to work with them and that I never came back or called. I know he works with many people so he got confused but that was completely untrue which he later admitted. I gave them a few chances as stated above. He said all he could do is appologize and help me next time. I posted that online and then received a call from the owner of Star Gmc quakertown. She said I was not being fair because I did not give them a chance since I took my car elsewhere for the tests, even thought I came during and after the tests. Her comment then was that she was not aware. She would have helped me more if she knew what was going on but obviously I was not important enough for anybody to mention it to her. But apparently thats the only way you will get "help". They already got my sale so they didn't seem to care. I bought a 2 year old car with 20k miles for $22k that burned through 1qt of oil every 2k miles. That's 2.5 out of 5qts if you change your oil every 5k miles. No wonder why my car was engine knocking, it barely had oil. I traded my car in for $16k. So I took a $6k loss. I would accept a $2k loss but $6k for a lemon car is crazy in less than a year and a half of ownership. All the owner would do is offer me a "sincere appology". Any one else want to be their customer? I will never buy from there or buy any GM vehicle again since they have that rule. If they would have honored their manufacturer warranty and fixed the engine, i would have drove that car for many years, if it lasted. Google GM oil consumption issue and you will see many others with the same issues. Good luck.