I bought this motor and boat used and have questions about winterizing it. I have had 2 strokes but this is the first 4. I have the shop manual but it doesn't say anything about winterizing. Next question is about the screw in plastic plug on the middle unit. The book just says water plug that seems to go into the oil pan. OK but what does it do. I took it out and looked in the hole and seen a small hole and another hole with some type of small bb in it. All help would be appreciated, thanks.