Overbased calcium sulfonate

Overbased calcium sulfonate (CAS 68783-96-0), also referred to as OBCS or sulfonic acids petroleum calcium salts overbased, is a high-basicity additive used across lubricant and metalworking fluid formulations.

Its reserve alkalinity neutralizes acidic combustion and oxidation byproducts, extending the service life of oils and protecting metal surfaces from corrosive attack in demanding industrial environments.

In engine and gear oil formulations, OBCS functions as a detergent additive, keeping metal surfaces clean by dispersing soot and oxidation deposits while maintaining TBN reserves.

Metalworking fluid manufacturers incorporate it into cutting and rolling oils to provide both corrosion inhibition and emulsification of oil-water systems for improved performance.

In grease production, it acts as a thickener and corrosion inhibitor, particularly in marine and heavy-duty industrial greases where water washout resistance is critical for the application.

Rust preventive coatings and preservation oils for steel and industrial equipment also rely on it to deliver long-term film protection against humidity and salt exposure during storage.

Overbased calcium sulfonate is supplied as a viscous liquid or oil solution, with TBN values typically ranging from 300 to 500 mg KOH/g depending on the specific grade required.

Technical and lubricant-grade specifications are standard, with product selection often driven by TBN level and viscosity. Drum, IBC, and bulk tanker quantities are the common supply formats.