looks like a base gasket leak like doc said..and that oil should be changed too man...
it's an easy fix.pull the front plastics and tank off,clamp the rad hoses with vise grips or just drain everything and refill,drain the cylinders (little 10 milimeter bolts on the outside of each cylinder),pull the intakes carbs and reeds,pull the head,pull the cylinders,replace the gaskets and assemble back together. remember to scrape any old gasket off the case and cylinder surfaces.good luck