....why our Lycoming engines call for 12 (or 8) quarts of oil, when they blow
out anything over 8 (or 6) quarts?

My old A&P, a real gray head with decades of aviation experience, mentioned
the reason to me in conversation today. Here's the poop:

When Lycoming was certifying these engines, they had to prove that they
could operate them for "x" number of hours at full throttle. (The number
bandied about was in the hundreds of hours, but no one knew for sure.)
Lycoming was not allowed to add oil to the engine during this certification
operation.

Obviously, in order to run at such high power settings for so long, you're
gonna need a lot of oil. Thus, the sump on my O-540 was designed to hold 12
quarts, while the sump on my old O-320 held 8 quarts. This ensured that
they would pass the certification test.

However, since they were certified with these over-sized oil sumps, that
became the only way they could be built and sold. This despite the fact
that anything over 8 and 6 quarts, respectively, ends up painting the belly
of our planes in normal operation...

So now you know...the *rest* of the story.... ;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"