Please keep me posted. Thanks
UPDATE: Probably not Piston Oil Rings. I finally got the report back and now it makes a bit of sense.
A couple months prior to this issue, I went into my dealer for regular service/ recall inspection. I came out with a check engine light on. I went back an hour later and they told me my gas cap was loose and no codes came up when they scanned it (bs). They turned the light off and of course, it came right back on. I scanned it myself and got codes for Evap/knock sensor. I called the dealership and asked to be seen again and they said it would be 1-2 weeks but just go ahead and drive it if it doesn’t get worse. This may have been my mistake. I drove it for those 1-2 weeks with obvious knock, getting like 17 mpg max when I normally average 30 (which I informed them about).
I finally take it in again and it turns out the technicians had the knock sensor disconnected from last service. Maybe if I was more handy, I would have thought to check that but you know…why should I have to troubleshoot diagnostics on my brand new leased car 🙄. Anyway, I drove a decent amount during that time, which may have resulted in engine damage. However, everything was normal until September when it just totally failed.
Looking at the service record, the damage seems more consistent with what I would expect from this situation, not the piston oil ring. However, I’m not a mechanic. I’m sure the dealership was happy they could just let Kia take care of the engine replacement! Haha. At the end of the day, it looks like it was likely their goof (and mine for driving it when my gut told me I probably shouldn’t have).