John_F wrote:
By flying at 8000 to 14000 feet for 41 hours
on a trip I only used 2 quarts in 41 hours. Since I was running wide
open throttle I had no engine manifold vacuum most of the time. It
would appear to me that the extra oil usage at part throttle was
caused by the oil being sucked down the intake valve guides.
Someone more knowledgeable may comment on this.

My guess would be that your engine makes only 50% or less, much less at
14,000 feet, percent power, and it won't use much oil at such low power
settings.