This is a topic where you will definitely hear different opinions based on marketing, scientific theories, and mine of course which is real world. As time has gone by what used to be the norm in changing you cars motor oil was every 3000 miles, now is some cases has been extended out to 7000 miles or more. So what has changed so much to extend the engines oil life? A more efficient engine maybe, more chemicals and additives added to base crude oil maybe, better quality metals and machining processes maybe. A lot of maybes and I truly do not know which one it is or is it any one of the above. What we see in our repair shop is real world consequences of neglected engines and the result is always expensive and a lot of times a big surprise, not an expense you were planning on, especially in today’s economy. My advice is to have your cars engine oil changed every 3000-4000 miles, the cost is very little compared to the cost to perform major engine work, the cost is so expensive in many cases it will total the vehicle.
If you do some quick math and you change your oil three times a year with an average cost of $50 = $150×10 years = $1500.00, I can assure you that $1500.00 is a small amount of money compared to $4000.00-$8000.000 to replaced an engine.