Total rookie question from a rookie rider. Researched every forum and data base as to what oil to put in my wrf426 2001. I know a 10w 40 4stroke oil, but do I go synthetic or semi. They all contradict each other and I want the best for my bike. I want to change the oil before I ride it, it also looks a little off coloured at the moment, a slight milky colour and smells funny. Sorry for the rookie questions.