[JFP in PA]

Originally Posted by Sputter

What am I missing here man?
A lower temp t-stat opens sooner (coolant a bit cooler than full temp) Once warmed up though, the t-stat would stay open no matter how early it opened no?

You are correct in your assumption that once at rated temp, the stat stays fully open, unless the ambient air is so cold it begins to pull too much heat out of the system. Think of the stat as controlling the minimum temp of the coolant (which it does in colder outside temps). Because it is fully open at a lower temp (160 degrees), the engine has a reserve of lower temp coolant in full circulation to absorb heat being put out by the engine and oil and carry to the radiators earlier than with a higher temp rated stat.

The only thing I can thing of is that after the T-stat opens it will close once the coolant temps drop below it's rating. So it's always opening/closing?

It can cycle, but usually only at relatively cold ambient temps. On a 70 degree day, once it opens, it usually stays open.

Open = more cooling. So a 160 will actually stay open longer than a 185 assuming the coolant temp can cool down below 185 degrees.

Correct. On a 72-75 degree day, open road cruising with a 160 stat, the coolant will actually drop well below 180 degrees (in testing, we saw 167-170 via the OBD II port).

The idiot gauge calibration isn't good enough to show a drop of 20 degrees?

The temp gauges in Porsches have been a sore point for years and across all models; they are notoriously inaccurate and non linear.

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