Not sure if it is kosher or not but I just raised my vent pipes 4 inches with a normal vented cap.
Never clogs and makes filling the blower a little easier for me.
I've never had any oil come out the vent or the seal.
Interesting turn of events. Manufacturer offers tips on prolong the life of your blower, while at the same time discontinuing said blower for a cheaper import in their new machine.