Bad Rod Bearings
I think it's unacceptable, I have changed the oil every 5000 miles, Used only Hyundai Oil Filters. Used only Mobil 1 5-20 full synthetic motor oil. I had to oil changed by the dealer at the first 3000 Miles. I had the coolant flushed at 60,000 miles and at 90,000 miles. I had the transmission flushed at 60,000 miles.