Frustrated and could use some help. Rebuilt my YSM 12 over the winter. Everything is new or overhauled from the fuel tank to the exhaust out the stern. After running at 3000RPM's for about 20 minutes out the harbour my power drops to around 2500 and further drops to the point I get nervous and shut down the engine and let it set for about half an hour. We seem to be able to continue at about half throttle and head back to dockside without incident. The 1979 Hunter 30 has a 3 bladed prop which the boat came with. A club member seems to thick that there is too much oil in the engine and it's getting splashed up into the piston cylinder after the engine gets hot and the oil expands and the engine is over working itself. The oil level is at the full mark but he expresses concern that it is to much because the engine is slated aft on it's motor mounts. The oil gets black real quick but no grit in it. The YSM manual states that the oil capacity is 3/1. Any ideas as to what the 1 means? Anyone else experience similar problems? Upsetting after dumping $2000 in new parts!!!