Last winter I installed a Safety-Stat I bought from NAPA. I didn't really want a Safety stat but that was what they had in stock because they not only fail open, they do that the first time the engine temperature exceeds some predetermined temperature that a truck engine regularly exceeds. On a long, hard pull both my 235 and my 261 will hit about 205 and sit there till the top of the hill.
Sure enough by the time I got home from Arizona the engine was taking too long to warm up and getting too cold on the down-hills. I never pegged the temperature gauge (212 version). This is not the first time I've had this happen. Lately, I replaced the Safety Stat with a regular 180 what with fall approaching. It's been over 90 everyday for a few months so I didn't worry about it over the summer.
