I changed engine oil of my new Getz at 2500 to shell helix 20W-50 mineral oil. Hyundai recommends 20W-40 for Getz. Later I discovered that shell helix 20-50 is thick oil, mainly suitable for older vehicles. On internet, I read that thicker oils are not good for new cars as it hinders the free flow of pistons and not good for run in of the car. Should I change my oil? If so, should I go for Hyundai oil, i believe Castrol or some other oil?