My view tends to be different. A few years ago, after one of those ad infinitum ad nauseum debates on when to change oil, I sent a sample to Blackstone at 8800 miles. It was Mobil-1 EP, and it was all okay, contamination; protection in every area. It would have been perfectly good for over 10,000 miles. It was a high mileage car, driven outside she snow zone.
Most people here make their decision on oil changes for emotional reasons, and believe their decision was total logic and science. They really have no idea how much contamination and remaining additives are doing.
But. to me, that’s okay. You need explain to no one when or why you change your oil. (EXCEPT YOU MUST COMPLY WITH MANUFACTURERS REQUIREMENTS DURING WARRANTY.)
The problem is when someone tries to convince others that his wild guess is pure science.
If you want to know when to change your oil, send a sample to Blackstone at, oh, say, 5,000 miles, then 7,500, (then ??? after the warranty is up.) I don’t mean take out a sample and wait to change it. Take the sample during oil change at that mileage. You will soon know when you should be changing it. After testing mine, I started changing that oil at around 7500 miles. (Warranty was long past.)
And, yes. you certainly can extend your oil changes with synthetic oil. To say not is a perfect example of confusing an emotional decision with science.
There are more reasons for oil testing than finding out when to change oil. Blackstone can tell you if something is going wrong or excessive wear inside the motor. Head gasket problems? The test will tell you. Bearing wear beyond the normal? it will tell you. Valve train problems? the test will tell you. Blow-by? ditto. Almost any serious problem in the motor will leave its trail in the oil tested.
Having said all that, I can see nothing really wrong with the 5,000 mile change. Sure, in a lot of cases, good oil is being wasted. But, at the same time, the odds you are ever going to harm your motor with over-extended oil are slim. For the cost of a motor, an oil change every 5,000 miles dwindles into nothingness by comparison. JUST DON’T TRY TO PRESENT IT AS SCIENCE.