I seriously doubt that the oil is the culprit to higher temperatures. How are you determining the temp is higher? If it is indeed significantly higher do the normal cooling system troubleshooting steps. Radiator condition & colant flow? Thermostat? water pump?
Coling system failure kills many times more engines than oil related issues. I lost a GM 350 v-8 to a bad waterpump..real quick. Gave A few warnings, runing hot then took a **** on the freeway dropped all the coolant out of the entire cooling system before I knew what was happening(no high water temp warning with no fluid) and siezed the engine before I could pull over once I knew what was occuring(odor tipped me off but too late).