Originally Posted by JARblue

An oil cooler is just a big heatsink for the oil. Setrab core is just a higher quality heatsink - cheap ones can get punctured by a rock while driving, which will really ruin your day.

The thermostatic sandwich plate closes when temps are cool and opens when temps heat up. This helps the oil in the engine heat up faster after a cold start than if it were being pumped through the oil cooler. The block off plate basically is a poor man's thermostat - thin piece of sheet metal and some hi-temp velco on the front of the oil cooler will do the trick - for when the cold winter air during casual driving is cooling off the oil too much.

The plate only shuts off the lines to the oil cooler - the filter is still working. That would a horrible design if not.

The oil pump is what moves engine oil through the oil filter. The oil cooler doesn't turn on and off. When you plumb in an oil cooler to the system, it just gives the oil another path to go. The thermostat controls that path and opens it at a certain temperature.