2004 mercury 15hp 4stroke oil

[outback32]

hi guys im looking to change the oil on my carbureated 15hp 4stroke. Ive seen some websites have 25w40 listed and others have 10w30. Im wondering what would be better for my motor. also some say conventional and others say semi synthetic. just trying to make sure i get the right oil thanks

 

[faztbullet]

Use only a FC rated oil......

 

[outback32]

The oil im taking about is all mercury oil. some say 10w30 some say 25w40 conventional or semi synthetic