When Valve Stem Seals(VSS) are going bad, blue smoke will appear upon acceleration, after starting or after idling for a minute or two. Typically not seen during normal driving, smoke will appear as you accelerate away from stopping at a red light. The worse your seals the large the cloud of smoke. Bad seals allow oil to be sucked into the cylinder from the valve cover during the pistons down stroke. While this condition alone will not directly damage your engine burning oil will lower your gas milage and reduce power. If left uncheck the burning could also leave your engine low on oil.
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Burning Oil - 3SI Wiki