How do you change the oil filter housing from a mk2 to a mk1 saxo?

To change the oil filter housing from a Mk2 to a Mk1 Saxo, first ensure the engine is cool and disconnect the battery. Remove the oil filter and drain the oil, then unbolt the oil filter housing from the engine block. Replace it with the Mk1 housing, ensuring all seals and gaskets are in place to prevent leaks, and then reassemble everything by reversing the steps. Finally, refill the engine with fresh oil and check for leaks before starting the engine.