Hyundai allows 5W20 (oil cap) , 5W30 and 10W30 (as higher temps warrant) ... Planning a drive from Georgia to the West Coast and back all on interstate / highway roads which is constant 55 MPH or higher the whole trip (except when passing through or near a large city) . I'm planning to run either M1 EP or Castrol EP 5W20 , 5W30 or even 10W30 which are 20,000 mile synthetic oils . My entire trip should be under 10,000 miles and once I return home I plan to change the oil and filter (Fram Ultra) . *Which oil do you go with and why ? Thanks in advance !