"A couple of months" tells us little about the number of hours. How many
hours on the engine since rebuild? What was done on the "rebuild"? New
rings (I hope), rechrome?

Darryl, I don't have my O-300 book handy, but as I recall when I overhauled
my engine the book recommended mineral oil for the first fifty hours.

When I overhauled the 182 jugs and rechromed them, the oil temperature ran
hot for the first ten to fifteen hours, and then dropped like a rock when
the rings finally seated to the chrome.

Jim



Gary Wilcox wrote:

I have a 1964 Cessna 172 (Continental 0300D) and the oil temp seems to be
running higher than I remember from last summer. Its still in the green
but
only a needles width below the red-line. What is normal? Conditions
during
the latest flight were hot and humid - temp at ground level was 92 and
relative humidity in the 90's.

The engine had all cylinders re-built a couple of months ago and I am
runnning straight mineral oil (Aeroshell 80). All of the baffles are in
good
shape and the mechanic sealed all of the seams with sealant during the
cylinder rebuild.

Leaning too much? Perhaps you aren't getting full rich... Makes a big
difference at low altitudes with our C172F... I dunno if I'd still be
running mineral oil, break in wasn't required, rings should be seated by
now, we run Aeroshell 100... Make sure all the baffles aren't folded,
putting the cowling on can sometimes bend them the wrong way...

There are STC's available for adding an oil cooler... And don't overfill,
too much oil might also cause an overheat issue. We run ours below 7
quarts but above 6.5...