Re: Winterizeing a 1998 merc 150hp, can som1 list the steps?
Use the "Search" function. There must be a hundred posts on how to winterize an outboard. But here are what needs to be done. If you don't know how to do each procedure for your engine you best let a shop do it or else buy a service manual for your engine.
1) Add fuel stabilizer (Stabil, SeaFoam, or any of the other gazillion products) to the fuel and run the engine long enough to get the treated fuel into the engine.
2) Change the lower unit lube.
3) Fog the engine if you feel the need.
4) Store the engine vertically so the water can drain.
5) Connect a battery maintainer on the battery (in or out of the boat) or remove the battery and store it inside. Charge it once a month or so with a portable charger.
6) Put it to bed.
