I just changed my motor oil (5W40) and installed a new thermostat (195 degree). I know the oil levels good but at times not always after the truck warms up the oil light will come on, mostly in traffic. If I drive on thr freeway at about 50-65 mph it will go out. The old tstat was missing the valve element so it might as well not had one in there. The heater wouldn't even work, the heaters hot now. I wonder if i should try a cooler tstat say 180 degree.