Which octane for new Ford V-10

Octane requirements increase as a vehicle ages. This is from burnt fuel deposits on top of the piston and combustion chamber(like spark plug deposits). With a smaller physical volume, and the piston pushing the same amount of air, it raises the compression ratio. Engineers call it "Octane creep". The process starts right away, but starts to be noticeable at about 30-40 thousand miles. That's why they almost never ping when their new. So, if you start with a compression ratio of 8.5, after a couple years it's higher than that and 87 octane fuel just doesn't cut it any more, and you need 89 octane. Add the extra load of an RV plus heat and you get problems. If it gets bad enough, you blow the engine with a broken rod or such. Pre-ignition can be a problem before you ever hear it. I have seen it on an oscilloscope, but that's another story. With aircraft we run 100 octane. No pre-ignition can be tolerated, else a cylinder blows off. My new rig is fine right now with 87, but I'll up it when it asks for it and probably be at 91 at some point. When someone blows an engine at 25-40 thousand, they get blamed for not changing the oil or some other neglect, when it's the fuel that's responsible all along.