Q: Engine knock, burned a lot of oil

The ticking sound is caused by the valves in the engine experiencing a low oil condition, the lower the oil gets the louder the noise. This is a well-documented problem for this series where the vehicle will excessively consume oil, sometimes as much as a quart every 2,000 miles! GM states this is due to faulty piston rings, which allow the oil to slip past the oil ring and enter the combustion area where it is burned along with the fuel, resulting in a severe oil loss, with no evidence of a leak, and reduced fuel economy (oil and gas mixed together do not burn well). You can reference Technical Service Bulletin (TSB) #01-06-01-011H, which addresses the issue of excessive oil consumption. The bottom line is that the pistons and rings all need to be replaced to correct this issue. While GM has been aware of the issue for some time, as evidenced by many internal memo’s, they are often slow to fix the issue at the dealership level. Make sure you check you oil level every 1,000 miles or so until the problem is resolved or you run the risk of running your engine dry and causing severe damage. If you have a warranty, have this issue addressed as soon as possible as it will not go away without proper repair. Even if you have no warranty, I recommend going into your local dealership to see what they are able to do, be persistent.