Posted for "George Braly" <gwbraly@gami.com>:

 In a normally aspirated engine,  at 15,000 feet… there is no such thing as
“aggressive leaning” - - -  just changes in mixture.
 

"""
Flying at 15000' going east, WOT, 2400 RPM, 14.5-15.5 GPH, 220 to 230 kts
ground speed with 30 kt tailwind; EGT @ 1260, CHT @330.  Fuel computer says
900 nm of gas left, 1000 nm to go, takes about 1hr to land, fuel, and get back
up in the air.
 
 To make the trip without landing, lower RPM to 2100, begin aggressive
leaning, engine sputters @ 9 GPH, enrich to 10 GPH, EGT's go up to 1300, CHT's
to 350, GS ~ 190-195 kts with same tailwind. Now fuel computer says 1200 nm
left, 1000 to go, have fuel margin and do not have to land.

 Am I hurting my engine with the aggressive leaning??
"""