Oil is going missing. Gremlins?
Buddy has a 95 F350 4x4 auto, has had quite a few minor problems with it, but has slowly worked through them all. In the past few months he has done glowplugs and injector seals, some seals in the HPOP, waterpump, just last week he did the gallery seals in the base of the turbo as it lost 8L of oil in about a 25km drive. So as it sits now, it has zero external oil leaks, and was running pretty good, rough idle and rough cold start, but useable.
In the last two days it has gone through 4L of oil, but he has no clue where its gone. Like I said, nothing dripping anywhere, no oil in the antifreeze. No clue where it is going. No extra smoke, or extra sticky coating in the exhaust.
His only guess is that he might have done something wrong and it is burning the oil right at the base of the turbo. Would it be hot enough to burn it up there and not end up with any extra noticeable residue in the exhaust or extra smoke? Any other ideas?