High altitudes and oil grades

[zachenbacher]

Hi,

today I took my P51 to a high level flight for the first time but encountered serious trouble with my oil system.

Flying at FL350 the temperatur was minus 55°C. The settings were 29 Hg and 2300 rpm. After a while I noticed the oil pressure shows around 150 psi and the oil temperature was around 60°C and decreasing. Some minutes later the oil pressure warning light came up.
I managed to descend and divert to an alternate airfield. At lower altitude and warmer ambient temperature all values coming back to normal.

I used the normal oil grade (1100) but I think the oil was getting to thick because of the low temperatures. So is the consequence I have to take the thinner oil to do high level flights were the temperatures are always as low as minus 50°C?

Thanks in advance
Denis

[zachenbacher]

Ah - found an answer in the forums!

The values I found are abolutely ok for high flight levels in the Mustang.

[robert41]

Keeping the MP higher and the RPMs lower will help keep temps happy at higher altitudes. I usually run 41MP and 2400RPM. Could go a little less RPMs, and sacrifice some speed.