Patent ID: 8076274

Claim:
A lubricating oil composition for a diesel engine, comprising the following components: (a) a lubricating oil basestock of lubricating viscosity; (b) an antioxidant component; (c) a detergent component; and optionally (d) one or more metal hydrocarbyl dithiophosphate compounds in an amount of from 0.0 to 1.8 mass % and/or (e) a calcium detergent compound; wherein the antioxidant component (b) is selected from one or more ash-free aminic and/or sulfur-free phenolic compounds in an amount of at least 0.6 mass % up to 3.0 mass % based on the total mass of the composition; and the detergent component (c) is an overbased magnesium compound having a total base number (TBN) exceeding 350 mg/g KOH selected from one or more magnesium sulfonates, magnesium salicylates, and magnesium phenates and which provide the composition with greater than 0.05 mass % Mg based on the total mass of the composition, and wherein the sulfated ash content of the composition is at least 0.6 mass % to not more than 2.0 mass % as determined by ASTM D874.