M-B Fuel Additive
 

Going where they have not gone before M-B has a fuel additive 000-989-25-45-10. The additive is to help prevent coking of the intake valves, specifically m112 and m113 engines. The word from Tech is it will not remove coking only prevent. When asked how often it should be used the answer was at every fillup. I have no price/availability as I'm on Christmas vacation with my Benjamin. I'll post additional details as they emerge.