In certain conditions 'too cool' could be a bad problem to have. For 35 years my dad would drive whatever vehicle he owned nearly 5 miles from home drieway to textile mill parking lot and back again 8 hours later.
At those lower temp engine areas like sheet metal rocker covers and top of the heads, the paraffin in yesterdays motor oils would set up like black candle wax everywhere. Then we would take the vehicle on a longer drive and the stuff would get hot and fall away, eventually clogging oil returns and even the pickup in the pan. I don't recall how many times he would have to pay someone to desludge an engine.
Quakerstate brand got a bad reputation during those times mostly for this issue.
Even though most mfgrs went to 195-degree thermostats we still saw the same sludge buildup in Fords thanks to their Havoline oil.
