You said you added a bottle of ARX and have already driven 1000 miles with it. When you get the car back fro the dealer, insist that they change the oil and filter, and drive some 1000-1200 miles. After that, do another full Auto-Rx treatment. I don't think this engine is toast, it's just not clean.
Continue with 3-4 oz of Auto-Rx when the last cleaning period is done.
Continue with 3-4 oz of Auto-Rx when the last cleaning period is done.