Many people assume that if they usually drive only short distances they don't need to change the oil as often as someone driving hundreds of kilometres a week.
Wrong. Stop-start driving a couple of times a day in the city requires more frequent oil and filter changes than driving regularly
at uninterrupted highway speeds. Stop-start drivers should change their oil every 5000km. Drivers who spend more time on the open road can double that. Check your owner's manual.
Vehicles that are taken out only once or twice a week or aren't used for extended periods should also have their oil changed more frequently because condensation, unburned fuel and other contaminants foul the oil, reducing its ability to protect against wear and tear.
Oil does not "wear out". It can be recycled again and again. What does get used up are the additives that help keep engine parts clean and free of sludge and carbon deposits.
The oil itself eventually loses its ability to hold contaminants and dirt particles in suspension and away from delicate moving parts. That results in increased friction and accelerated wear and tear.
