As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OIL TEMP CONTROL VALVE (VERNATHERM) IMPROPERLY ASSEMBLED CREATING CHRONICALLY LOW OIL TEMPERATURES WHICH WERE UNNOTICED IN WARM WEATHER BUT BECAME EVIDENT IN VERY COLD WEATHER. TCM SPEC IS GASKET SURFACE TO BASE OF ADJUSTING NUT TO BE 1.807 +/- .003 INCHES. THIS UNIT FOUND AT ABOUT 1.850 INCH.