The myth of changing engine oil

I'm due to change the engine oil in my car pretty soon but I've just read a Yahoo report that it may not be necessary for car owners to change their engine oil every 5,000 kilometres.

According to a recent study by the California Integrated Waste Management Board, 73 percent of California drivers change their oil more frequently than required. (...) Besides wasting money, this translates into unnecessary consumption of US$100-a-barrel oil, much of it imported.

Using 2005 data, the Board estimates that Californians alone generate about 153.5 million gallons of waste oil annually, of which only about 60 percent is recycled. Used motor oil poses the greatest environmental risk of all automotive fluids because it is insoluble, persistent and contains heavy metal and toxic chemicals. One gallon of used oil can foul the taste of one million gallons of water.

It’s been a misconception for years that engine oil should be changed every 5,000 kilometres, even though most auto manufacturers now recommend oil changes at 8,000, 12,000 or even 16,000-kilometre intervals under normal driving conditions.

Greatly improved oils, including synthetic oils, coupled with better engines mean longer spans between oil changes without harming an engine. The 5.000-kilometre interval is a carryover from days when engines used single-grade, non-detergent oils.

Note: In the above report, I have changed 3,000 miles to 5,000 kilometres. There are other miles-to-kilometres conversion elsewhere.