Behold:
Mocal Sandwich Plate 20mm Thread w/ 200 Degree T-Stat
MOC-SP1FT-HT is the 200 F version of
MOC-SP1FT which is the 180 F thermostatic plate that Modshack used in his
scratch built oil cooler
Not the cheapest solution but it it won't begin to send oil to the cooler until temps reach ~190-195 F