Everything old is new again. Model T's also lack a dipstick. You check the oil by opening petcocks on the pan. If it drips out the top one, it's full. If not, you add oil. A common aftermarket upgrade was to install a sight glass on the lower petcock allowing for a visual check.
(I can remember this piece of trivia I heard eons ago, but why I walked into the kitchen is a mystery.)
