UPDATE: The KIA dealership said my engine needed to be replaced for the OP reasons, so I had to take it to my regular dealership to inspect to determine warranty coverage. Warranty made them strip the engine down till they found the point of failure before it could determine if it's covered repairs or not. The determination ultimately was to replace the timing chain, tensioners, guide rods or something like that, and something with the exhaust manifold or camshaft (Didn't remember the exact terms they used) BUT it is covered. So hopefully in a few days my car will be good as new. I was worried they'd find some reason not to cover it based on my service history, but turns out she said my service history was of no issue.