Forgot to mention in my previous post, read up on LS engines that lose oil pressure before you buy an engine. I don't know exactly what years are affected - somewhere around 2013 for sure - and I don't know if it's only 5.3's or all of them. My father in law has a 5.3 of that year that started throwing a check engine light for a bad oil pressure sending unit and they found that it actually had low oil pressure. In his case there was a simple O ring that was causing it to bleed off but I guess it can also be wiped out cam bearings. The shop he took it to said there were a few years around his that had big issues with that and they saw a lot of them.