Originally Posted by wstar

?? Unless it's changed since I bought mine a few years ago, Mocal's plates don't work like that - although maybe that's just how we're using words

When cold, the bypass and the cooler passages should both be 100% open. Just due to being the path of least resistance, most of your oil will bypass the cooler, but the passage itself is fully open. Then roughly from 175-185 the thermo spring closes off the bypass passageway, which then forces all your oil to go through the cooler passageway. But nothing ever closes (even partially) the passageways leading to/from the cooler. In any case, if the thermo were stuck open he'd see higher temps, not lower.