What is the correct, Lycoming preferred, procedure to check the oil level in a 0-320 engine? I pull the dipstick up out of the tube enough to see the oil level, and add a quart when the level is at 6 1/2 quarts. I understand not to run the oil level below 6 quarts. Does Lycoming want the level checked with the dipstick screwed into the tube or not screwed into the tube?