It won’t hurt to change the oil every 3000 or 5000 miles. But it will barely help anything. A waste of time, money and resources. All new cars will easily last 15000+ miles between oil changes with no harm. Recommendations are usually every 7500 miles by manufacturer’s now, except for dusty conditions, etc. But this is merely a precautionary overkill by the manufacturers, with nothing to lose by overkill. Sooner or later, the EPA will be using oil consumption in its total fuel economy calculations and the oil change interval will be of importance. GM will have onboard oil condition sensors on some models which measure essential oil properties such as acidity, oxidation, viscosity etc. The actual oil change time will be precisely determined, no sooner, no later.
Oil always blackens with use, its lubricating and protection are not necessarily diminished in relation to this “property” alone. This is another scam that oil change “mechanics” use–they show the blackened oil on the dipstick and scare the owner into an unnecessary oil change, or worse, an engine oil “flush”. Many people will pay the unnecessary expense because they don’t know the facts and find this “evidence” hard to counter.
Oil changes in the near future will be easily be as infrequent as every 25000 miles. The goal is the 100000 mile interval. Remember that trans oil used to be recommended changed at 25000 miles. New cars now routi9nely have 100000 mile trans oil change intervals. The 3000 mile change intervals are for old pre 90’s clunkers, are out-moded, and only are for car nuts with nothing better to do, and other obsessive-compulsive types.