Alkaryl Sulfonates 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 sulfonates are one of the main families of lubricant additive components that help increase the performance and life of the engine.  Lubrizol alkaryl sulfonates ( 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

Alkaryl sulfonates are produced by neutralizing an alkaryl sulfonic acid, a benzene ring with sulfonic acid substituent groups and one or more long-chain alkyl substituent groups, with a base metal, typically calcium hydroxide, to form the corresponding metal 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 alkaryl sulfonate.  Alkaryl sulfonates 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 alkaryl sulfonates have been assessed as alkaryl sulfonates part of the Petroleum Additive Alkaryl Sulfonate Category under the U.S. Environmental Protection Agency (EPA) voluntary High Production Volume (HPV) Challenge Program. The HPV assessment has shown that they have a low order of acute toxicity by oral, dermal, and inhalation routes of exposure in animals.  Some alkarylsulfonates may cause skin or eye irritation.  Low TBN (total base number) calcium sulfonates are skin sensitizers at high concentrations while high TBN calcium sulfonates are not sensitizers.  Repeat dose studies in animals have found that the extent and nature of systemic effects following repeat dose exposures vary depending on the alkaryl sulfonate, dose, and route of exposure and duration.  They are not expected to cause reproductive effects based on a one generation rat reproduction study of an alkaryl sulfonate that was deemed an appropriate analog predictive of the potential reproductive toxicity of the other compounds in this category.  No mutagenicity or clastogenicity was observed across a range of alkaryl sulfonates.  Based on these results, they are not expected to be carcinogenic.

Environmental Effects

The environmental effects of alkaryl sulfonates also have been assessed  as of the Petroleum Additive Alkaryl Sulfonate Category under the U.S. Environmental Protection Agency (EPA) voluntary High Production Volume (HPV) Challenge Program.  The HPV assessment has determined that alkaryl sulfonates are not readily biodegradable and do not contain functional groups that are susceptible to 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.  Generally they are of low concern for acute aquatic toxicity although some may cause adverse effects in aquatic organisms.

Regulatory Information

These additives are subject to the European Commission REACH (Registration, Evaluation, Authorisation and Restriction of Chemical substances) regulation, which was implemented to ensure that chemicals in commerce are safe for man and the environment. The registration and submission of Chemical Safety Reports for these substances will be submitted to the European Chemicals Agency (ECHA) by Lubrizol in accordance with the applicable deadline.  As noted in Lubrizol safety data sheets, alkaryl sulfonates have gained acceptance in major industrialized countries through global notifications.

Exposure Potential

Lubrizol alkaryl sulfonates are sold to industrial customers who formulate engine oils.  Workers in these industrial exposure scenarios, professional workers and consumers can be exposed to alkaryl sulfonates via dermal contact.  The potential for inhalation exposure is limited by their low volatility.  However, some industrial operations are that are conducted under elevated temperatures may increase the potential for inhalation exposure.  Because formulated products contain low level of alkaryl sulfonates 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 alkaryl sulfonates are designed to meet the special protection needs of all engines.  Their excellent physical and functional properties make them ideal for use in lubricant to inxcrease the durability and performance of engines.  Alkaryl sulfonates have been well-studied.  Some alkaryl sulfonates can cause skin or eye irritation, but they are not known to cause skin sensitization.  While they have a low potential to cause acute toxicity, some alkaryl sulfonates can cause systemic effects following repeated exposure.  Generally, they are of low environmental concern, but some may cause adverse effects in aquatic organisms.   The use of appropriate engineering controls, work practices, personal protective equipment and environmental release controls and practices provides effective risk management.