Without getting into a long story, my A4 is running without a thermostat (the PO took it out and the intake from the water pump to the thermostat housing is blocked). The engine used to run hot, but after a flush it has run progressively cooler from about 140 down to around 100 now. I have replaced both the sending unit and the temp gauge, both of which are operating correctly. the water here in Puget Sound is still cold these days, but the engine stays at 100 or 110 degrees. My question: other than fouling the plugs more quickly and getting less than optimum fuel mileage, will low operating temps hurt the engine long term?