Lead skies
A recent patent from British Petroleum (BP) makes a disturbing admission: piston-engined aircraft need such high-octane fuel that tetraethyl lead is still added to it to keep its octane rating up. So while all new cars can now use unleaded fuel, aircraft engines are still dropping lead from the sky. BP claims that the new high-octane fuel, a mix of triptane, iso-pentane, iso-octane, toulene and methyl tertiary-butyl ether can change all this. This new fuel, says BP, raises the octane num- | her to over 100, which makes it a usable, lead-free aircraft fuel.