You're not gonna get an accurate reading when it's warm. I always check mine when it's cold to check for consistency. By time your engine's cold, most of the oil is back in the pan and you can tell how much is truly in your sump. When you're checking it warm, a lot of the oil is in the head and you're not gonna get a good reading. When I check my engine oil cold, it's just a little bit over the full mark but if I check it warm, it's only between the marks.