Water Pump and Thermostat

[epapp]

The only time the low temp tstat would lower temps of the engine is when you are cruising on the highway and there is much more cooling capacity (because of a low ambient outside temp) than there is engine heat being transferred into the coolant. The tstat would stay open lower than the normal 186 and allow the engine to 'feel' the cooler coolant temps, probably stabilizing around 167, 169.

As soon as the engine starts putting out more heat than some specific amount (which isnt hard to do, in 90F weather my temps go up to 200 even at 70MPH), the lower degree tstat will just dampen the heat up cycle because of the coolant flowing around earlier in the heat up cycle.

City driving, hot weather driving, idling in traffic etc will all still produce the same steady state temperature, because the low temp tstat only allows wiggle room in the scenario that I described.