| abstract |
PROBLEM TO BE SOLVED: To provide a lubricating oil composition having improved piston cleanliness and having a sulfate ash content of 1.0% by mass or less. A lubricating oil composition produced by containing or mixing a large amount of lubricating oil and a small amount of (A) a dispersant additive composition and (B) a detergent additive composition, comprising: The oil composition provides a sulfate ash content of 1.0 wt% or less, such as 0.3 to 0.9 wt%, preferably 0.5 to 0.7 wt%, and a total base number (TBN) of 4 to 9.5, such as 5 to 9, preferably 6 to 8.5. Yes, having at least 0.08%, for example 0.085-0.115%, preferably 0.09-0.10% by weight of nitrogen from the dispersant additive composition, based on the weight of the oil composition, derived from the detergent additive composition Said lubricating oil composition having at least 25 mmol, in particular at least 28 mmol, such as 35 mmol or less, per 1000 g of oil composition. |