Quote Originally Posted by GasGuzzler View Post
You might have an issue as mine has a 160 in it and barely cracks 175 if ever. Then again, no tstat can make one run hotter because the coolant doesn't stay in the radiator long enough.

Closed loop starts at 153 degrees. Put too low a tstat in and you'll get P0128. With add on OEM efans and a 160 mine will set this code in the winter when the auto AC turns on the compressor and therefore the fans and the coolant never get warms enough for closed loop hence the P0128.

I would not say never go below 180 'cause a 160 does have a proper application but my 160 needs to be a 180 and I WOULD NEVER RECOMMEND NO TSTAT TO ANYONE for a driver, only a track only, TRACK ONLY vehicle.
i just looked up a stock tune file for a 02 4.8 silverado and closed loop is 131*