What is an oil leak filter base and when does it need to be replaced?
I think what you might be referring to is an oil filter adaptor that is leaking. The oil filter adaptor will bolt on to the engine block and the oil filter will screw on to the adaptor allowing the oil to flow through the filter from the engine block. If this is leaking it is a good idea to have it repaired as soon as possible because if your engine runs low on oil for too long, engine damage can result. As far as I know there is no maintenance interval for replacing anything here. If oil is leaking from your adaptor, the gasket between the engine block and the adaptor has failed and will require replacement to correct the leak. I would recommend having this service performed by a professional.