Choosing the right dispersant for your lubricant formulation—or fuel additive system—requires understanding both the application conditions and the chemical types of dispersants available. A dispersant’s job is to keep sludge, soot, varnish, and other contaminants suspended in the oil or fuel, preventing deposits and improving cleanliness.
✅ Key Factors When Choosing a Dispersant
1. Type of Application
Application
Dispersant Requirements
🔧 Engine Oils
High thermal stability, soot handling, ash control
⚙️ Gear Oils
Moderate dispersancy, thermal stability
🛢️ Hydraulic Fluids
Good water tolerance, oxidation resistance
⛽ Fuel Additives
Clean fuel injectors, prevent deposit buildup
2. Dispersant Chemistry
Type
Ash Content
Key Features
Typical Use
Succinimide (PIBSA-based)
Ashless
High dispersancy, thermally stable
Engine oils (gasoline/diesel)
Succinic Ester/Amide
Ashless
Excellent for low-ash formulations, good thermal stability
Low-SAPS oils, synthetic oils
Mannich Dispersants
Ashless
Strong detergency and dispersancy, nitrogen-containing
Gasoline engine oils, dual-function
Phenate/Sulfonate blends
Ash-containing
Often used for combined detergency/dispersancy
Marine oils, older engine oil formulas
🔍 PIBSA = Polyisobutylene Succinic Anhydride, the building block of most ashless dispersants
3. SAPS Level Requirements (Engine Oils)
SAPS Category
Dispersant Choice
High SAPS (e.g., CI-4)
Use traditional PIB succinimide dispersants
Mid SAPS (e.g., CJ-4)
Lower-ash variants or esters/amides
Low SAPS (e.g., CK-4, SN+)
Ashless dispersants like ester-based or amine-free
4. Viscosity and Solubility Compatibility
Match the dispersant’s base oil compatibility (Group I/II/III/PAO/esters)
Choose dispersants with a suitable viscosity range for your formulation
Liquid vs. solid dispersants: Liquid forms simplify blending; solid forms may require heating or solvent cuts.
How to choose dispersant?
🧪 Example Product Types
Commercial Name
Type
Typical Use
PIBSI-1000
Ashless dispersant
PCMO, diesel oils
Dispersant MDI
Mannich-based
High detergency + dispersancy
PIBSA-Ester DPE
Ester type
Low SAPS/eco oils
Additive Package DCP-4
With dispersant
CF-4/CH-4 engine oil systems
⚠️ Tips for Selection
Balance with detergents (calcium/magnesium sulfonates) to maintain cleanliness without ash overload.
Consider thermal stability if operating in high-temperature conditions (e.g., turbocharged engines).
Use bench tests like:
Sludge handling tests (CEC L-109-16, ASTM D6595)
Panel coking, TEOST, or filterability tests
💡 Choose dispersants based on application, ash content needs, thermal demands, and formulation compatibility. Ashless succinimide dispersants are the most common for engine oils, but ester- or Mannich-based dispersants may be better for low-ash or high-temperature systems.
