Is it a good idea to move from Synthetic oil to normal oil ?

[dogsridewith]

Yes. Higher ambient gives higher coolant and oil temperature. Thermostats, or most thermostats, don't flip from full closed to full open at one temperature. In cold winter, a temperature gets maintained with little coolant flow. So the thermostat isn't very far open. In sweltering heat, the temp may not stabilize until the thermostat is nearly open. And more open takes a higher temperature. The thermostat has an opening versus temperature curve.

And coolant doesn't cool some places so well. The oil pan can be getting radiation and conduction from sub freezing pavement/air or very hot asphalt and the air it heats.

[tmontague]

Originally Posted by dogsridewith

Yes. Higher ambient gives higher coolant and oil temperature. Thermostats, or most thermostats, don't flip from full closed to full open at one temperature. In cold winter, a temperature gets maintained with little coolant flow. So the thermostat isn't very far open. In sweltering heat, the temp may not stabilize until the thermostat is nearly open. And more open takes a higher temperature. The thermostat has an opening versus temperature curve.

And coolant doesn't cool some places so well. The oil pan can be getting radiation and conduction from sub freezing pavement/air or very hot asphalt and the air it heats.

Very much so. In the middle of winter the oil will not go above 180F (give or take a few degrees) unless in a high.load condition. The convection from the oil lan and cold air is much too great to keep the oil at summer operating temps.

On the flip side, in my 2zr with 5w30 full syn oil (factory fill is 0w20) and coolant temps reaching 230F, the oil climbs to just above 280F and stays there until a cool down lap. That is at full WOT and close to redline rpm's though.