As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT ENGINE HAD HIGH OIL TEMPERATURE DURING CRUISE. 97C AND CLIMBING. DESCENDED TO FL250, TEMPERATURE DECREASED FOR A FEW MINUTES AND BEGAN CLIMBING AGAIN. EMERGENCY DECLARED AND DIVERTED. LANDING WAS UNEVENTFUL. MAINTENANCE REPLACED THE LEFT ENGINE OIL COOLER THERMOSTATIC BYPASS VALVE. A SUCCESSFUL OPERATIONAL CHECK FLIGHT WAS PERFORMED. AIRCRAFT WAS RETURNED TO SERVICE.