"Hi all, I just changed my lower unit oil with Lucas 80W-90 Gear Oil. The folks at Lucas says that the oil is excellent for outboard final drives. The weight of the oil is not what concerns me. I am wondering if I get any damage to my seal, and leak some water, how is this oil going to mix with my oil? And will this oil foam up on me? Maybe someone has used this, and had success. Give me some insight.....Thanks Steve"