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

 Craig,
 
   Currently  I am operating an  IO-550 at about 101% of rated torque ( 2500 x
WOT, rather than 2700 x WOT) at cruise, and then at 100% of rated Hp for
takeoff and climb.
  
 We do this at all altitudes and essentially 100% of the flight hours (except
for descent and landing) , since the engines are turbo-normalized.
  
 We actually have been having rather excellent results doing this over more
than 200 engines.
 
  We do however have them VERY well baffled and keep the CHTs at or below 380F
.   We prefer straight wait oil, but many are run on multi-weight.
 
   What is your understanding of the automotive experience with the
multi-viscosity oils ???
 
 
 
 Regards,  George