Cannondaleriders

Ok so I'm guessing I'm looking at the product of a chemical reaction of green coolant and magnesium? I was wishing it was air bubbles - not so much. So I switch to the evans coolant and do i need a new cover? I was kinda hoping a good flush and new coolant would do the trick. Makes sense to me that would work as the corrosion is confined to the valve cover and possibly the impeller, although the impeller must be working because the quad doesn't over heat? I guess I'm looking for a person that has much more experience with this than I to point me in the correct direction.

impeller is not mag either plastic or aftermarket aluminum. I would say the evans is safe unless the valve cover is ate clear through which will show up in the engine oil. but is is hard to tell how far the coolant has ate through the cover and could possibly break through at any time and then you will be running with bad oil.