However, keep in mind that the recommended 7,500 mile oil change is for vehicles which are driven under ideal circumstances. Realistically, what most of us think of as “normal” driving is in fact “severe service” driving. This includes frequent short trips (less than 10 miles, especially during cold weather), stop-and-go city traffic driving, driving in dusty conditions (gravel roads, etc.), and driving at sustained highway speeds during hot weather. For this type of driving, which is actually “severe service driving”, it’s a good idea to change your oil every 3,000 miles or six months.
Some motor oil manufacturers suggest that you change your oil every 3,000 miles or three to six months regardless of the type of driving you do.
A new engine with little or no wear can probably get by on 7,500 mile oil changes. However, as an engine accumulates miles, it will leave more unburned fuel in the crankcase which dilutes the oil. This causes the oil to break down. So if the oil isn’t changed often enough, you can end up with accelerated wear and all the engine problems that come with it (loss of performance and fuel economy, increased emissions and oil consumption).