Overview:
The phosphorus content of new oil is typically associated with zinc
dialkyldithiophosphate antiwear
additives (ZDDP). Antiwear
additives are used to reduce wear by limiting the friction of moving
parts. They do so by forming a thin protective film on metal
surfaces. Low phosphorus could indicates that there may not be
enough anti-wear protection of the oil, however this could be
compensated by adding a non-phosphorus containing aniwear additive
High Phosphorus levels can lead to emission system failures
due to catalytic converter poisoning
The current API standards for
passenger car engine oils (API SM, SN, and ILSAC GF-5) require
phosphorus to be between 600 to 800 ppm to provide sufficient wear
protection while guarding against catalytic converter poisoning
(shown by the area in green).
The amber area takes into account the precision of the test method.
Results in the red area do not meet current API passenger car
motor oil standards.
