The purpose of a t-stat is to keep the coolant in the engine to help it heat up faster. The lower temp T-stats merely open sooner than the higher temp ones. Once that temperature is reached, it opens all the way up and functions the same as the higher temp ones. If the t-stat temp is way too low, the engine will take forever to heat up to operating spec (if it ever does). It is not a cure for anything since an overheating engine will still overheat.