The oil does not drain to bottom of the reservoir in my AC filters because there is a tube from the bottom hole that goes up 4-5 inches (I'll post photos later today). The oil has to drain out by going into/over the top of the tube or into a hole near the top of the tube (similar to LONGBOX55's description of his Fram filters).
However,
"Different oil filter canisters fill and drain differently.A sludge siphon was a handy device for getting oil out of the bottom of canister that did nor drain to the bottom and did not have a
drain plug near the bottom of the canister. wokri,
You have looked inside your filter canister. When you take out the filter element, is there a tube in the center of the canister?
