Abstract: This invention relates to a diesel engine lubricating oil composition comprising or resulting from the admixing of: (i) base oil, (ii) a functionalized polymer, (iii) an overbased magnesium based detergent, and (iv) one or more, optionally borated, higher and/or lower molecular weight PIBSA-PAM dispersant. The composition has a total sulfated ash of less than or equal to 0.9 wt. %, a kinematic viscosity at 100° C. of 5 to 20 cSt, a total phosphorous level of less than or equal to 0.120 wt. %, and a total sulfur level of less than or equal to 0.35 wt. % and provides a Detroit DD-13 scuffing test result of at least 31 hours. Also provided are a method of making the composition, a method of lubricating a diesel engine, a method of improving wear performance and engine cleanliness and reducing emissions of a diesel engine, and a diesel engine oil additive concentrate composition.