That looks to me like a lot more froth than would be expected with normal operation and with normal temperature variations. I think the 180° thermostat is a good idea if you don't have that now. Also, I would run the truck fast enough to get the engine fully to normal operating temperature, at least a half hour at normal temperature. After that, I would do a cylinder leakage test to see if there is any leakage between the cylinders and the cooling system. Next, or before doing the leakage test if you want to, I would take the cover off to see if there is any evidence of head gasket leakage. If you don't find any evidence of cooling system leakage, then I would watch everything for a while- the condition may only be the result of weather and operating conditions.
Harvester
