Chevrolet Repair: Oil Change/Timing Chain, chevrolet astro, high mileage

Question
Hi Rich
(1)OIL CHANGE
Own 1989 Chevrolet Astro,(4.3 liter-V6); 142,000 mi. when bought; couple different mechanics think engine replaced in past. I've added 116,000 mi.,runs good, never valve cover leaks. Use Castrol "High Mileage,10W40". Change every 3000-3500 mi. Guy at Auto Zone says 3000 mi. too often; says companies trying to sell more oil. Gets dark caramel look around 3000 mi. Should I change then, even if 3000 mi. oil change  too soon? Better to go by color of the oil, and not mileage?
(2)TIMING CHAIN:
Timing chain has 116,000 mi. How soon should I change? Not making any noise right now, doesn't miss, run rough, or act like timing's off.
Thank you very much for your opinion!
Mike Eidson

Answer
Hi Mike,
If it doesn't hurt your pocketbook to change it at 3000 miles, keep doing it, and you will save on parts in the long run.
I have NEVER heard of anything being damaged by changing the oil too often, unless someone leaves the drain plug loose, but I'm sure you won't do that.

Keep that timing chain lubed up like you have, and I feel it will go 300,000 miles plus. What damages them is the long intervals between oil changes, not the short ones.

In my opinion, you are doing everything right.

Van