I have a 2014 Kia Optima, I've had it since Oct. 2013. A nut came lose in the trubo. The dealership service center will not repair it even though its under warranty. We did 2 oil changes with them and since did our own as the dealer said we could as long as we kept our receipts. The turbo is an external turbo and has nothing to do with the oil itself. We provided the receipts as requested. Now they say the receipts show no mileage so the car was not maintained. Even if the car was never serviced (which it was) the turbo has nothing to do with the oil. How can they NOT repair the turbo?