Abstract: A lubricating oil having an ashless nitrogenous TBN source together with ash containing detergent having a TBN in excess of 100, a source of magnesium, and metal dihydrocarbyl dithiophosphate with predominantly or exclusively secondary hydrocarbyl groups is described. It comprises a major amount of an oil of lubricating viscosity having a sulfated ash content between 0.35 and 2 mass percent and A) a nitrogenous TBN source selected from the group consisting of ashless nitrogen containing dispersants, ashless nitrogen containing dispersant viscosity modifiers, oil soluble aliphatic, oxyalkyl, or arylalkyl amines and mixtures thereof; B) a metal salt of an oil soluble acid having a TBN in excess of 100; C) at least 500 ppm (mass) magnesium; and D) at least one metal dihydrocarbyl dithiophosphate. The nitrogenous TBN source provides at least about 1.5 TBN to the finished lubricant. The metal salt of an oil soluble acid provides at least about 40% of the total TBN of the composition.