Bought a boat with a Johnson 175 2 stoke engine. The oil tank was filled with quick silver, the bottle was left in the battery compartment but I threw it away, not thinking about it. I called a marine dealer and he said to put evinrude xd30 in it. I would rather keep what was in there and not mix it. What should I do. Can u drain the oil or does it matter. Think I should just put quick silver twc3 and go with it. any help would be appreciated.