Low-ash lubricating compositions

A passenger car lubricating composition having a low sulfated ash content, the passenger car lubricating composition comprising:

• one or more base oils of lubricating viscosity;
• an antiwear system including one or more ashless phosphorus-containing antiwear compounds and, optionally, one or more metal-containing antiwear compounds, and wherein a phosphorus weight ratio of phosphorus from the one or more ashless antiwear compounds to phosphorus from the one or more optional metal-containing antiwear compounds is about 50:50 to about 100:0, wherein the ashless phosphorus-containing antiwear additive is a triester of a dithiophosphate having two oxygen ester moieties and a sulfur ester moiety, wherein the ashless phosphorus-containing antiwear additive has a molecular weight of at least about 490 g/mol, and wherein each oxygen ester is derived from 4-methyl-2-pentyl alcohol and the sulfur ester is derived from dibutyl maleate;
• a sulfated ash content of about 0.75 weight percent or less as measured pursuant to ASTM D874;
• about 700 ppm or less of total phosphorus contributed by the one or more ashless phosphorus-containing antiwear compounds and the optional one or more metal-containing antiwear compounds;
• a detergent system having a weight ratio of magnesium-to-calcium of about 2.0 or less;
• and
• a TBN ratio of TBN measured per ASTM D4739 relative to TBN measured per ASTM D2896 of at least about 60 percent.