Very informative, thanks Crumpp.
In Britain, there was a terrible problem for a time with the fuel. They used TEL as an octane booster, and it was mixed on site.
Evidently it was not mixed until homogenous. The TEL came out of the fuel in the intake and intercoolers on the P-38's, and they'd detonate badly. The TEL would then get into the engine in high concentrations and foul the plugs.
With the P-51, they said you never knew if it was rough because it fouled a plug or because it detonated and cracked a head. You only found out when it was too late if the head was cracked. Once the coolant leak got bad and the temperature went up, the Merlin would sieze in about a minute, no matter what.
Doolittle worked for Shell during peacetime, and he got Shell to solve the fuel problems in early 1944.
