If only doing 4K miles a year and it involves lots of short journeys there is a good case to made that the oil should be changed at 6 months ! If the oil does not get up to working temperature then a lot of combustion by-products will not be burned off and this will degrade the oil & cause wear. It is kinder to the engine to do 25mile + journeys rather than 5 mile ones even though the 25 mile trips may result in much greater yearly mileage.