ASTM D7946-14

Note 1: In new and used oils, the constituents that may be considered to have characteristics influencing the i-pH value include organic and inorganic acids, esters, phenolic compounds, lactones, resins, salts of heavy metals, salts of ammonia and other weak bases, acid salts of polybasic acids, and addition agents such as inhibitors and detergents. “Initial” is used to differentiate from aqueous systems. The analysis is terminated after a defined time interval whenever equilibrium conditions, as known for pH measurements in aqueous systems, are not reached (see 3.1.1.2)