If the car is reading anything below the full mark, I add. My moms 2007 Grand Prix with the L26 and it consumes about 1/2 a quart over 1K. My 1999 Camry 5S consumes NO oil over its 5k intervals. Both cars have 167k and are running M1 0w40. I don't see an issues with adding unless you are A.) about to change the oil. (Previously mentioned) or B.) the engine is still hot.