Oil filter assemblies

An oil filter assembly for an internal combustion engine of an outboard motor, the assembly comprising:

• a base having:
• a high-pressure inlet port receiving oil into the base;
• a filter-mounting interface configured to receive a filter;
• a drain-back port configured to receive a drain-back insert of the filter;
• and
• an engine-mounting interface configured to mount the base to the engine, the engine-mounting interface including a high-pressure outlet port and a low-pressure outlet port providing oil from the base to the engine;
• wherein the base provides fluid communication between the high-pressure inlet port and an inlet side of the filter and between an outlet side of the filter and the high-pressure outlet port when the filter is installed on the filter-mounting interface and the drain-back insert is within the drain-back port;
• wherein the base provides fluid communication between the drain-back port and the low-pressure outlet port when the drain-back insert is not within the drain-back port;
• and
• a clean oil fill passageway in fluid communication with the low-pressure outlet port.