While Lindy did use a LOP setting to fly the Ryan across the Atlantic in 1927, the Lindberg myth about LOP in the P-38 persists even though it is contradicted by those who were there. According to M.F. Kirby, P-38 ACE from the Pacific who was present for two of Lindy's talks about extending range, he claimed that he never talked about mixture management at all. That's consistent with my own knowledge of the P-38 Allison set-up which could NOT be manually leaned. It had only four mixture positions: Emergency rich, Auto rich, Auto Lean and Idle cutoff. Auto lean like all other WWII aircraft was set for Best Power, 80dF ROP. One P-38 pilot who actually flew with Lindberg on a combat mission said that Lindy seemed to change his mind about slow-flying when he saw his first Zero up close and personal.
According to Kirby, Paul Murray and others, Lindy ONLY talked about using high MP with low RPM to extend range. After attending a Juvat Reunion (80th FG) with Kirby, I had that confirmed by at least a dozen other P-38 pilots from the time. ALL of them claimed that Lindy's method, while useful in peacetime was a disaster in combat. The reason was that it took too long to come up to dog-fight speed from the extended range speed when you saw the enemy. Not one of them said they knew anyone who used Lindy's recommendations. They kept speed up and S-turned behind the bombers they were covering, always ready to engage at a moments notice.
"I never was interested in saving gas. I was too busy trying to save save my arse."
M.F. Kirby