<Doomsayer>
All of the crowd crowing about running 93 octane all the time, every time aren’t hurting anything, but there is zero evidence in hand that the truck will not run on 87 octane AND it explicitly states in the manual that 87 is the minimum required fuel. Jeff-O has indicated pinging on 87 octane. I’ve run 87 since day one without incident. Sure, it’s possibly a mistake in the manual... On a truck that took years of R&D, on a 2nd generation of their workhorse engine, that is shared in the Ford GT, with a very large reputation at stake. Or it’s possible that Ford knew exactly what they were doing when they put 87 octane in the manual.
I think back in the 70’s a tank of ‘bad gas’ was potentially more likely and could happen then. Maybe it could even happen now, but the regulations on fuel in the USA are super stringent and bad gas is something that you get when a tank sits for several months on end unused without a stabilizer.
If you’re getting a persistent knock with 93 gas, you need to use the warranty. It’s possibly defective knock sensors