I've resurrected this old (ancient?) thread to explain how the problem of chronic cold operating temps - water and
oil - was solved.
I worked with a mechanic in Manhattan to (1) insert a sleeve in the by-pass, restricting the flow around the thermostat and (2) install a 180' themostat. With the reduced rate of flow through the by-pass the cooling system is no longer adequate to maintain water temperatures much below 78'C, even with air temperatures below 50'F. When air temp rises to 74'F or more, water temperature rises to 88-90'C, causing the thermostat to open. Once open, water temps hold 83'C when air temperature exceeds 100'F.
Oil temperature is consistently 74-76'C when water temperature measures 83'C. If air temperature drops below 74'F, water temperature hovers around 76-78'C and
oil temperature ranges from 64-68'C.
There are no problems driving in traffic and the fans come on only after the car has been run hard and parked, and then only for a minute or so. Water temperature never exceds 93'C when the fans begin.
Barring better advice from this group, I belive the problem has been solved.