In order to use this fuel, the only requirement for 70 percent of general aviation piston airplanes is to use an oil that contains certain additives, such as Shell’s 15W50, W80Plus or W100Plus, according to Hjelmberg. For an additional 20% of the fleet, mostly light-sport airplanes, the fuel can be used with no special requirements. But for the remaining 10 percent, it’s a little bit more complicated. Turbocharged, higher horsepower engines and “special” airplanes such as warbirds, can’t use the fuel without modifications. But there are solutions out there that would allow these operators to use the 91/96 UL as well. Unfortunately these modifications would be quite costly, but if the FAA is going to spend years and millions of dollars, why not take that money and give it to these airplane owners instead? The money could also go to new fuel stations, in which case there could be a transition period when both 100LL and unleaded fuels are available.