I have a 200 merc 2.5l with a new (2 season) sei replacement lower unit. I religiously change the lower gear oil at the end of each season. I pulled the boat out of my yard and parked it in the street as i get ready to put it in the water for the season. i left the motor tilted up for the last week and there are drips of oil on the street below the lower unit. Oil was water free and when I changed it three months ago. any thoughts?