2006 Chrysler Town and Country burning fuel

I purchased this '06 Town and Country in June. The first time the oil light came on I brought the car in for its first oil change. Nothing was noted about being low on oil. 2,000 miles later the oil light came on again. Both times I didn't bring the car in right away (not understanding the importance/significance of the oil light and getting oil in right away). The second time (Feb), the engine started to make a loud noise, but I thought it was from something else and drove with it like that for a few days. Turns out, I had less than a quart of oil in the car. Other than in this situation, I'm usually a pretty smart person. So, I'm thinking there was a problem when I bought the car because I've never had an oil light come on before. It turns out the engine is burning oil like crazy. I put in 2 quarts of thick stuff and another 3 quarts of regular oil. Then 250 miles later had to put in another quart. It's not looking good. My mechanic suggests I just trade it in and get rid of it. I'm trying to determine if I should do that, or repair or replace the engine. I understand this is costly ($2-4K) depending on the extent of damage to the engine. I still owe $8K on the vehicle. What do you think I should do?