I dont think the motor oil would have been your problem. If you were running 100mph, at 25 psi, you were revving what... close to 4krpm?
maybe you touched a valve. timing tooth jumped, or timing belt is missing a cog/old/loose.? or cam slipped. then you shut it down hot, turbo still spinning while no oil goes to it, while everything else cools at different times. maybe the cyl walls cooled before the pistons and rings, which caused them to stick and possibly distort, still giving you some compression but not what you had. then as everytihng was cool, the starter broke free the stuck or burned or distorted rings/pistons. it still goes, but you now have some blow by, as long as the oil is thick, it will boost the compression a bit, enough to keep running, untill something lets go, piston, rod, valve, or possability even the turbo. or the timing belt. ... maybe water in the fuel, or a clogged fuel filter.
