You can simply add Techron fuel treatment to the fuel tank every 5/10,000 miles, in the proper concentration. This will help with the valve contamination as well the injectors
drive it hard. the 5.3 DI does not have this issue near as bad as many other models, and I believe if you drive it a little harder that the valves with get hotter and burn it off better. I have 110k on my 15 sierra and it runs like a top / does not burn a drop of oil.
fuel additives do not help with carbon buildup on the valve in a DI engine.
I had a suburban with a 6.0 with over 300k. The rear main was pouring but besides that no problems.
Those 6.0s will last forever. Mines at 230k currently. Never moves unless it痴 towing.
Well...
Our mechanic says GM recommends periodically cleaning the intake valves using their top engine cleaner. He says when he did it the first time, he thought he killed his engine, it smokes and shudders for about 25 minutes. However, it appears to work and he did it to both of our engine replacements, and will do it every few oil changes.
So, just be aware of that potential issue, and it's a recommended maintenance item, so it should probably be done at the recommended intervals.