You can fill the pan with a measured amount of water when it is removed from the engine. Measure from the top of the pan to the water level (measure A). Then take that measurement (measure A) and with your dipstick installed and with your
oil pan still removed, measure that distance (measure A) down from the bottom of your block. Mark that on your dipstick. Also if you run with a windage tray you can add more
oil (xtra qt )without a problem.
John