Hello all, I am looking for info on a magnum 350. I drained the oil and 2 quarts of water emptied first before the milky oil. Having problems getting old oil filter off to start with. The previous owner said no cracked block. The oil level was high when I purchased.I know that going in. I have been told that if I take the boat in to be have the block checked they will fill it with new oil and if the water shows up in the oil immediately it is a cracked block and not a head gasket or other gaskets. Is this how they test the block?? Thanks