Okay I purchased a tree sprayer. A older Bean f It has on it a 65 horse V465D Wisconsin engine gas. Good strong engine IMO. It runs solid adn smooth but I have a concern. The valves are not hardened as these engines I think were built during the leaded fuel era. I know you can buy a lead substitute but it is nothing more than just a oil, something like Marvel Mystery oil. So I was thinking of just adding a quart of diesel to a tank, 30 gallons of gas, in fact I have. I have ran it about 14 hours so far and it sounds and runs smooth. However I wanted to hear what a mechanic has to say. Or someone that has knowledge.