This system has been proven many times to last a lot longer than 30 minutes.
Well my friend I flew the 61 for 22 years, also in the Beaufort so we may even have flown together at one time so I think I know that a/c pretty well. She is a fine old ship, but that emerg lube was to lube the Babbitt bearings so that the whole a/c did not become a magnesium fueled fire ball within seconds of the Babbitts running dry. It was never intended or advertised as a "run dry" MGB.
Really? Many times? Can you give some examples?
I know of the incident off the East Coast where a T fitting broke and pumped ALL the oil overboard, even the emergency lube sump. That machine was ditched.
As much as I love the 61 and have great respect for it, in a loss of MGB oil I'll take a 139 any day.