CHP2RA,
Oil temperature above 100 C (212 F) and less than 110 C (230 F) when fully hot is preferable to sustained
oil temps below 100 C to eliminate any moisture that might be acquired due to the combustion process. Also, modern
synthetic oils are more resistant to viscosity deterioration and oxidation than conventional petroleum based oils.
I used to live in Texas and added an
oil cooler after one summer when sustained ambient air temperatures exceeded 100F for several days. Under those conditions, my water temperature rose above 212 F and a noticeable drop in oil pressure was experienced in stop and go traffic. Now that I live in SoCal, I doubt that I will experience those conditions again.
John