I changed the oil and filter in my mercruiser 5.7 today-ran it for about 20 min in the lake, oil pressure was about 70 at operating temp, 3500 rpm. All of a sudden, oil pressure went to zero, I shut that engine off, got back to the dock with other engine. Opened the engine compartment, oil everywhere. Filter still tight, I’m at a loss on this one. Any ideas?