Many good ideas offered. The best one was calling the optics manufacturer to ask their specific recommendations. The lens coatings are the heart of the optic performance today as much as the actual glass itself. While there are a very small number of glass manufacturers and glass compositions, there are as many coatings as there are scope manufacturers and scope tiers. Coating life is essentially the life of the scope. Not worth the risk to use a product on the lens/coatings that my shorten the coating life in any manner. Application technique, including lens cloths, can also be as important. Protect the coating, protect the scope. Just a really, really old guy's thoughts.