1. Get an oil analysis from Terry Dyson, he'll tell you what's going on inside your engine. A HDEO 15w40 like you are using sounds like a good choice.
2. Fogging oil is a protecting oil you spray through the intake while it's running to protect parts before storage. It's more commonly used on boats and jetskis, but can be used on cars. I have a pair of SeaDoos and I am able to find it at the local parts store, however, if you can't get it there try your nearest local watercraft dealer.