I have meticulously had my oil changed every 3500 miles, I use the best oil for my Yukon XL. I have done every preventive maintenance based on the owners manual and from the dealer suggestions. For the past year I smell burnt oil. I do not see any oil whatsoever on the ground. I have had my engine steam cleaned several times to see if there is a leak on top by some valves? I'm not sure what the mechanic called them. He said there is nothing leaking anywhere but he said my engine is probably burning the oil faster than normal. In between oil changes I have to add oil to make sure I don't run out. This is really upsetting to me since I have no clue what needs to be done other than to replace my engine he said. Which will cost me several thousands of dollars. With the amount of miles my car has it should not be having this problem yet. A friend of mine has a Yukon XL with 250,000 miles and does not have this problem.