@ G35COUPE
I put 235,000 on a Mazda 626 and I had the oil changed every 5-6,000 miles. It was a 2.0 4 cyl 5 speed. I only used conventional oil in it with zero engine problems. The people I sold it to are still driving it.
In my current daily driver, Contour SVT, I do basically the same procedure...now at 123,000 miles...9 years old with no problem. I do flogg it good fairly often.
I've had many cars before those and most of them I put at least 90,000 on with no trouble.
I had a friend with a Toyota Cressida who changed his oil at 10,000 mile intervals...he used whatever Amoco's synthetic was. He put 300,000 trouble free miles on it.
I don't recommend that everyone change the oil like I do however I think changing every 2,000 is overkill....but if it works for you do it.
You have to keep in mind that oil companies do sales jobs on the industry that influences some of these recommendations etc. also.
BTW, I used to sell Royal Purple in the mid 70's when you could hardly give it away. It wasn't synthetic then IIRC but it just had no brand value.