Quote Originally Posted by 06T200 View Post
Ouch. Sorry you only got 2k miles on that job. I'd guess someone cut some corners, never a good idea unfortunately.
You said the oil was very thing, which leads me to believe that coolant has entered the crank case through either a bad head gasket or cracked block. Look under the oil cap to see if their is excess moisture. You might even want to drain the oil.

However, your best bet is to go back to the shop that did the work and see what they can do for you. Did you get paperwork from them after the work? Do they have a warranty period? It sucks to say, but if you have to pay out of pocket again for this mess, you're better off selling the car. A 2005 Aveo with 140k miles is worth less than $2000.