Polyisobutylene Succinimides 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. 


Polyisobutylene succinimides (PIBSA) are used to make dispersants that are used in tailor-made formulations to meet the challenging demands of engine oils.  Lubrizol polyisobytylene succinimides are critical engine oil additives that keep engines clean by dispersing harmful debris generated during operation that can thicken the oil, cause wear, and plug the filter.  They reduce the formation of deposits on metal surfaces and inhibit soot agglomeration via stable micelle formation.  Their dispersant action 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

Polyisobytylene succinimides commonly are produced by reacting polyisobutylene succinic anhydrides with an amine.  A highly refined lubricant base oil is used as a solvent during the manufacturing process and remains in the final product to maintain stability and physico-chemical properties.  Molecular weights range from 500 to 10,000 Daltons, but more commonly are in the 1,000 to 3,000 Dalton range.  They are not expected to partition into water or air because of their low water solubility and low vapor pressure. 

Health Effects

The health effects of polyisobytylene succinimides have been assessed as part of the Petroleum Additives Succinimide Dispersants Category under the U.S. Environmental Protection Agency (EPA) voluntary High Production Volume (HPV) Challenge Program.  Polyisobytylene succinimides have a low order of acute toxicity based on oral and dermal studies in animals and are not expected to cause skin or eye irritation or sensitization.  Based on the analogs that have been tested, they are not expected to cause any adverse effects following skin contact or if accidentally ingested and do not pose a reproductive or developmental toxicity hazard. The absence of adverse effects is consistent with the expected low bioavailability due to their high molecular weights.  Because no mutagenicity or clastogenicity has been observed with Polyisobytylene succinimides, they are not expected to be carcinogenic.

Environmental Effects

The environmental effects of polyisobytylene succinimides also have been assessed as part of the Succinimide Dispersants Category under the U.S. Environmental Protection Agency (EPA) voluntary High Production Volume (HPV) Challenge Program.  The HPV assessment has determined that polyisobytylene succinimides are not readily biodegradable and do not contain functional groups that are susceptible to hydrolysis.  They are not expected to undergo photodegradation.  Their low water solubilities indicate that water is not a target compartment, limiting the potential for bioaccumulation.  Results of ecotoxicity studies also indicate that they are of low concern for acute aquatic toxicity.

Regulatory Information

Polyisobytylene succinimide 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 registrations and Chemical Safety Reports for these substances are submitted to the European Chemicals Agency (ECHA) in accordance with the applicable deadlines. As noted in Lubrizol safety data sheets, polyisobytylene succinimides have gained acceptance in major industrialized countries through global notifications. 

Exposure Potential

Lubrizol polyisobytylene succinimides are sold to industrial customers who formulate engine oils.  Workers in these industrial exposure scenarios, professional workers and consumers can be exposed to polyisobytylene succinimides 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 and the end use engine oils contain relatively low levels of polyisobytylene succinimides, 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 polyisobytylene succinimides 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.  Representative polyisobytylene succinimide analogs have been assessed under the EPA HPV program.  They are not known to cause skin or eye irritation or skin sensitization.  They are of low health and environmental concern.   The use of appropriate engineering controls, work practices, personal protective equipment and environmental release controls and practices provides effective risk management.