Being more or less the SP / GF6 / D1/Gen 3 rated flagship 0W20 , 5W30 synthetic oils of Mobil for North America , it is believed according to newer data that esters have been reduced in the M1 EP oils . If this is the case , how has M1 changed the EP formulation and still continue the cleaning / performance M1 EP oils are historically noted for with higher ester amounts ?