Today when I went to refuel my car, there was a newbie who gave me Regular Plus (89octane) when I actually asked for Supreme Plue(94 Octane)..(it was a full service gas station)..I immediately stopped him when I notice and fill the rest of the tank with the Supreme Plus. Now the question is, would the mix of gas damage my car, especially its engine? I drove a '99 C280....any input is appreciated. Thank you