A remote oil filter housing lets you take the filter off the side of the engine and mount it somewhere sensible, which is often the only workable answer in an engine swap where the standard filter now fouls a chassis rail, steering shaft or exhaust. Used together with a take-off plate or sandwich adapter on the block, it puts the filter where you can actually reach it for servicing and gives you a natural place to tee in an oil cooler. Mount the housing securely to solid structure, keep the feed and return lines as short and as gently curved as you can, and always confirm you have connected feed and return the correct way round before starting the engine.