Hi brownrice,

I've always done similar mileage in all of my cars - I've always changed the oil at least twice a year. If you do lots of short journeys you are effectively warming up the engine just enough to get (damp) air to condensate on the inside of the engine. In the old days oil and water would sort of mix to make a sludge (emulsion) that was noticeable - however these days modern oils contain anti-sludging ingredients so you probably won't see any evidence of this. But it doesn't mean that water isn't there. As it is commonly agreed that the majority of engine wear occurs when you start an engine you are better off changing the oil more regularly (and thus getting rid of the unwanted) than if you were doing say twice your annual mileage.