Actually, it's probably not even pertinent if the oil is plus/minus a quart. However, I kinda like to see it 'just so" also. The owner's manuals always say get it hot and level, and let it sit for a few minutes, so the best possible scenario would seem to have it right at the top of the full mark after it had sat hot for about 10-15 minutes. I know the oil runs down for a pretty long time, cause when I change it, it's still running out a bit after 15 minutes with the drain plug open.