Heads and blocks are cast iron, which transfers heat very slowly. Your pistons are aluminum, and they get a squirt of oil at each revolution from the opposing connecting rods. The oil gets hot before the coolant for reasons mentioned earlier but still, your oil pump sucks up hot oil and distributes it all around your engine.
Bottom line; your cooling system also cools the oil, where water jackets are near oil passages in the block and heads.
FE engines have a series of oil plugs along the LH side of the block and one at the oil filter, for your "OIL" light sender. Any one of them can be used to pick up oil for your cooler.
Since oil carries much more heat than water, flow can be slow.
I have often wondered why OEMs don't use oil heat for the cabin because it gets hot right away. This is where a high volume oil pump shines... - Dave