He is ahead $ by far for one reason, curiosity is another reason. Fact is he knows his engine is in good condition running these extended miles having a quality report to back it up. First long mileage was by accident. I really was cringing at what that test report was going to find.
I am NOT saying AMZ/OIL is better than other oils but I guarantee they are better than most. FYI they started the Synthetic Oil craze in the 70's. PenZoil was so threatened by them that the took AMZ/OIL to court over the "Z" and so the "S" now looks like a "Z" backwards.
If this sample comes back good to go then he can just change it at that mileage from now on. FYI he is a Landscape contractor and his truck gets driven 50 miles each way during the week pulling the landscape trailer so it's light duty for that engine.