Primary Function

• Suspend carbonaceous and other insoluble particles in the oil.
• Prevent deposit formation on pistons, rings, and other hot engine surfaces.
• Maintain oil cleanliness and improve engine efficiency.
• Extend oil drain intervals and engine life.

Mechanism of Action

Dispersants are polar molecules with:

• A polar “head” that attaches to the contaminant particles.
• A non-polar “tail” that dissolves in the base oil.

This amphiphilic structure allows them to surround particles (like soot or oxidation products), keeping them finely suspended and preventing coagulation.

Main Types of Dispersants

• Ashless Dispersants (most common): Do not contain metallic elements. Derived from organic nitrogen or polybutenyl succinimides/succinamides. Preferred in modern formulations due to lower ash content and better emission compatibility.
• Detergent-Dispersant Packages: Dispersants are often combined with detergents to offer both particle suspension and surface cleaning.

Chemical Families

• Polyisobutylene Succinimide (PIBSI)
• Polyisobutylene Succinic Ester (PIBSE)
• Mannich Base Dispersants
• Borated Dispersants (for improved thermal stability)