Keep in mind the system used on this and most othe WWII engines is
similar. The oil is filtered, then "dumped" back into the pan. Modern
engines filter, then deliver to the bearings. This is one of the reasons
why this motor usually needs rebuilt by 50,000 miles. Very few MB/GPWs
hold up to 100,000 miles. But that's been good enough to keep them around
50 years!