I was wondering this exact thing. I kept thinking the next paragraph would be about a UOA but I never saw it???And the reason I do that is because the engine oil turns into copper color, like something is wearing inside of the engine.
My only question is why haven't you sent the used oil in for an analysis? You have spent plenty of money with maintenance so the cost of checking the oil is nothing in comparison. You may find out why the oil is changing to a copper color and be able to make a decision based on facts rather than just a guess.
Beyond that, I think considering a '12 Kia your "forever car" and doing a "full restoration" is an odd choice. Very odd. I could see it on some Toyotas or Hondas....even select VW's. I could even see it on certain "classic" domestics and just about any full-size truck from the Big 3 (or ANY Tacoma)
That said, some people like blondes, some like brunettes and some chase the redheads.....whatever floats your boat....if OP wants to die on the Kia hill, that's his choice