REFLECTOR: Oil Type

[Tom]

How hot is your oil?? Have you gone the 2nd cooler route? Anyhow, multi 
vis is a mistake at high temps (unless it is a synthetic which you can't 
really use with leaded fuels). The base oil in multi wt is the lower 
number, as it wears the high vis (top number) decreases. If you live in 
a warm climate there is very little benefit to multi wgts as cold starts 
are their best feature. Going to 120 (60 wght) is possible but if you're 
uncomfortable with your oil temps don't give up on trying to fix.
My plane has updraft cooling, had only one cooler and very small cooling 
inlets when I first got it. I played with various things for several 
weeks to get the oil temps down. I wound up getting a 5 row stewart 
warner as a 2nd cooler and was able to place it on the top baffling. 
Initially I blasted air to it with a 3 inch duct shared off of induction 
air via a Y. While later working on hot CHTs I found that the ducting 
wasn't necessary as there was plenty of air flow through the cooler (hi 
pressure/low pressure on opposite sides of the baffling). I went from 
235+ down to 185 with this setup. The Lycoming gurus say that the engine 
wasn't set up to pump oil through 30 feet of rigid line. Probably why we 
don't get much heat out of it either when it's cold. Tom