Originally Posted by robbyredneck
from the way the gm oil flow diagram reads it looks like the port on the left comes from the oil pump. i stuck a zip tie up from the filter perimeter side and saw it through the left hole. the right side looks as though it is fed from the center portion of the filter aka the outlet. now i know that means there would be a bypass of the filter and only creates a pressure differential for the cooler. thats the way it looks. maybe somebody with some concrete knowledge will chime in.
You must plan on using the style block that comes with an oil cooler correct? When I took my original one off the block it is split so that makes sense to me.
The style that completely blocks both ports off, like the one I got for a Camaro, loops one port to the other. If it is tapped then there would no way to distinguish filtered versus unfiltered.