By all means only send the car in to the dealer at the scheduled intervals, where they will change filters as well as oil and carry out a battery of other checks. But in between visits to the dealer do an oil change yourself or have your local non-franchised workshop do a quickie oil change for you. If you regularly drive in dusty conditions, change oil religiously every 5 000km. In any event, regardless of distance driven, engine oil should not go unchanged for more than six months. If you can, avoid driving on gravel roads and in dusty conditions.
Dust accelerates wear and tear in all mechanical systems.
If you regularly drive in dusty conditions then halve your oil-change and service intervals. Keep your car garaged. There's nothing that detracts more from the value of a used car than faded paint, cracked dashboards and sun-damaged seat covers. And keeping your car out of the rain as much as is practicable helps fight rust and damp in carpeting and body insulation. Wash your car weekly, by hand, and not in those machines with spinning brushes that put microscopic scratches in your paint and catch on trim.