General aviation are perhaps the most cautious and wary ICE users around. Most of the engines used in GA, Lycomings and Continentals, are essentially 1960s designs with very well known cost, performance and reliability characteristics.
That is not to say change is impossible, GA's overdue changeover to unleaded gasoline seems like an inevitability. Unleaded gas is already being approved for many of these engines, like new production O-360 engines (which date back to the 1950s.)
> General aviation are perhaps the most cautious and wary ICE users around.
That depends on if you're describing the pilots or the ~manufacturers~ Textron. The experimental fleet has been pretty adventurous and it's a fast growing fleet. I think most of the conservatism in GA ICE tech has been driven by the broader issue of consolidation into a near monopoly on the cheaper end of the market. If you have no competition then why bother innovating?
It starts with GA pilots being very conservative with what kinds of planes they invest in, since planes are huge money sinks already. The old engines have very well characterized reliability and cost, so pilots know what they're getting into and can accurately plan for all their expenses. New planes/engines are proposed fairly regularly, but generally fail because there are too many unknown factors that buyers are wary of.
That is not to say change is impossible, GA's overdue changeover to unleaded gasoline seems like an inevitability. Unleaded gas is already being approved for many of these engines, like new production O-360 engines (which date back to the 1950s.)