Alkyl Phenate Sulfides in Engine Oil


Lubrizol engine oil additives are designed to meet the special protection needs of all types of engines ranging from those in heavy duty vehicles, passenger cars, and marine vessels to smaller ones in recreational vehicles and power tools.  Lubrizol has utilized its in-depth knowledge of chemistry, technology and the additives market and decades of experience to develop products that meet not only basic technology needs but to provide novel, cutting edge innovations.


Detergent phenates are one of the main families of lubricant additive components that help increase the performance and life of the engine.  Lubrizol alkyl phenate sulfides (APSs) are critical engine oil additives that clean the engine and provide antirust protection.  Their detergent action helps neutralize acids produced during fuel combustion that can damage engine parts.  The detergent also helps keep small particles suspended so that they can be removed by the oil filter and not build up in the engine.

Physical and Chemical Properties

APSs are produced by reacting alkyl phenol sulfides with calcium hydroxide typically to form the corresponding calcium salt.  A highly refined lubricant base oil is used as a solvent during the manufacturing process and remains in the final product to maintain the stability of the alkyl phenate sulfide.  APS are complex reaction mixtures.  They are viscous liquids that have a low water solubility, a low vapor pressure and a high octanol-water partition coefficient.

Health Effects

The health effects of APS have been assessed as part of the Combined Alkyl Phenol Sulfide and Alkyl Phenate Sulfide Category under the Organization for Economic Cooperation and Development (OECD) voluntary Screening Information Data Set (SIDS) program.  The SIDS Initial Assessment Profile (SIAP) has determined that APSs have a low order of acute and chronic toxicity but may cause slight skin irritation.  Their high lipophilicity, high molecular weight, low water solubility and lack of toxicity following oral and dermal administration indicates that oral and dermal absorption and subsequent distribution are expected to be limited.  The low vapor pressure for these substances also indicates that inhalation is not expected to be a route of exposure under normal use conditions.  Varying levels of unreacted components, however, can affect the hazard of some products including the potential to cause repeat dose systemic effects and adverse effects on reproduction. 

Environmental Effects

The environmental effects of APSs also have been assessed as part of the Combined Alkyl Phenol Sulfide and Alkyl Phenate Sulfide Category under the (OECD) (SIDS) program.  The SIDS Initial Assessment Profile (SIAP) has determined that APS are not readily biodegradable and do not undergo hydrolysis.  Because of their low vapor pressure they are not expected to partition into air to any significant extent.  The calculated bioconcentration factors for these substances indicate that they have low bioaccumulation potential.  Results of ecotoxicity studies also indicate that they are of low concern for acute aquatic toxicity. As noted for health effects, varying levels of unreacted components can also affect the ecotoxicity hazard of some products.

Regulatory Information

APS monomers and other reactants currently are subject to the European Commission REACH (Registration, Evaluation, Authorisation and Restriction of Chemical substances) regulation. Lubrizol is working with suppliers to insure that the registration and Chemical Safety Reports for these substances are submitted to the European Chemicals Agency (ECHA) in accordance with the applicable deadlines. Lubrizol is also the APS itself.  As noted in Lubrizol safety data sheets, APSs have gained acceptance in major industrialized countries through global notifications. 

Exposure Potential

Lubrizol APSs are sold to industrial customers who formulate engine oils.  Workers in these industrial exposure scenarios, professional workers and consumers can be exposed to APSs via dermal contact.  The potential for inhalation exposure is limited by their low volatility.  However, some industrial operations that are conducted under elevated temperatures may increase the potential for inhalation exposure.  Because formulated products contain low level of APSs, the exposure potential for professional workers and consumers generally is much lower.  The extent of exposure varies depending on use conditions such as closed systems and the duration and frequency of use.  The potential for oral exposure is limited to cases of accidental ingestion. Indirect exposure via environmental media is expected to be negligible because of their low water solubility, low volatility and low levels in formulated products.

Risk Management

Information on the safe handling of these products is provided to workers who make the products and who formulate engine oils through dissemination of material safety data sheets.  These documents provide a broad range of safety information including hazard warnings and risk management measures.  They note engineering controls, work practices, and personal protective equipment that are needed during the manufacture and formulation to control exposures. Good industrial hygiene practices also are used to avoid skin contact.  Environmental risk is mitigated by controlling  spills and environmental releases. 


Lubrizol APSs are designed to meet the special protection needs of all engines.  Their excellent physical and functional properties make them ideal for use in lubricants to increase the durability and performance of engines.  APSs have been well-studied.  They have a low potential to cause health and environmental effects.  However, varying levels of unreacted components can affect their hazard.  The use of appropriate engineering controls, work practices, personal protective equipment and environmental release controls and practices provides effective risk management.