How do you determine if an engine is burning oil?

Answer 1

White or bluish/white smoke coming from the tailpipe is oil. Black smoke is unburnt gas. So if you notice a drop in the level of oil when you check it with the dipstick and have that: the white or bluish smoke, you are burning oil. Could be piston rings, especially on a high mileage engine, valve guide seals, (that will cause a lot of smoke upon start up, the oil has leaked past the valve seals in to the combustion chamber while sitting) but the basic answer to your question is the smoke