I had a ticking noise coming from the engine bay on my 2015 Silverado 5.3 which was somewhat quiet after buying the truck but could be heard. Around 7,000 I took the truck because it got progressively louder. I was told there was a service bulletin on this and was normal noise to be heard from the engine(high pressure oil pump etc....). This ticking noise became louder to where it could be heard over my CAI. I took the truck in and had it diagnosed. It ended up being a failed lifter on the valve train. From there it just snow balled, effecting the camshaft causing pieces of it to break off which ended up scoring one of the piston walls. The truck needed to have a whole new engine block put in along with all new pistons, valve train and camshaft. the truck was in the dealership for almost 4 weeks. My advice is take in your vehicle if you hear any abnormalities from the engine while you have warranty, better to be safe than sorry and end up spending 8-10k in repairs. Thankfully, my warranty covered my issues....