From a Professional tech,…
From a Professional tech, any engine any make, the first oil change should occur at 500 miles, the second at 3,000 miles and the third at the OEM interval. I have a 14 Silverado with the 5.3. I change my oil about every 10 months or at around 10k miles. I did the valve cover gaskets and the engine was clean besides the typical varnish in an engine. I'm due for my next change this weekend. It all boils down to how you drive. Does your engine reach operating temp for long enough when you drive? I have a 25 mile trip to work, so I get 50 miles daily with over 20 miles on a highway. Get an oil analysis done at each oil change, even if it's done at a shop, bring the bottle and ask them to fill it up. Have them remove the drain and wait 5 seconds before collecting the oil so the results are consistent. Or get a vacuum pump and collect the sample before you take it in. Take the sample the same way each time. They can also find issues before they become a mechanical failure.