2013 Hyundai Sonata. Had oil changed they put
synthetic oil in it and over filled about a quart. 2
days later less than 100 miles and the motor is
locked up. Could it be from changing from regular
oil to the synthetic oil
The oil type would not be the cause but over filling it could be. I think they may owe you an engine.
That Sonata is covered up to 120k miles regardless of how many owners the car has had. There is a known defect in the engine crank case with the crank itself. Go to a Hyundai dealer and get it fixed. https://www.nhtsa.gov/vehicle/2013/HYUNDAI/SONATA