>Latter test indicates electric fan needed - maybe a higher pressure cap
>(however, the thought of higher cap pressure sort of worries me - could
>it blow out my head gasket?)
Not likely to blow the head gasket, but might blow your heater core.
An additive like water wetter could be added, which acts as a corrosion inhibitor, and surfactant, which allows a better bond between the coolant and the hot metal parts it is cooling.
Doesnt increase the boiling point, but does reduce the engine temperature.
I'd spend $10 here before I put in any fan.
Jarrid Gross