Paul S - The Opel Olympia car (and I am sure other models) used the 1.5L engine which seems to be a general jack of all trades motor like the Willy "go devil" engine was for cars and things such as generators, compressors, welding machines. There where four "phases" of the 1.5L P1 thru P4 the folks in Germany where pretty excited I had a original to vehicle P1 engine. Like the "Go Devil" the 1.5L engine had a very long production run right up into the late 1950s, maybe even the 60s with P4 engines.
Sentry Duty - Yes the long tube is like a PCV valve, it is packed with steel wool in the end to condense oil vapour which then would drip down into a small square dish welded to the body bottom that also serves for catching oil when the drain plug is pulled, notice how the two are together.
The "trumpet" is vent and oil filler cap, and should point forward on a car, it even says FRONT (in English) and has a arrow to remove any doubt in the matter. On a Kettenkrad I do not think it makes any difference, and pics in the wartime manuals show it pointing both ways.
Late war, and things where certainly not turning out the way the Germans had hoped so they simplified the vehicle in a number of areas and deleted the oil filter and used just a steel line in its place. Earlier Kettenkrads had a filter housing installed. Interestingly enough the sad piece of sh!t and neglected Kett on display at the CWM is fitted with a 1939 Opel Car motor (and a couple other things) that tells me the Germans where harvesting and rebuilding automobile motors (and outdated early kett parts) for the war effort and to keep production up and vehicles going out the factory gates back in the day.
