Succinimide dispersants — made by reacting polyisobutylene-succinic anhydride (PIBSA) with polyamines (TEPA, PAM, HPA) — keep soot, sludge precursors and oxidation products in stable suspension, preventing engine deposit build-up, filter blockage and varnish. This guide covers mono vs bis vs borated architectures, conventional vs HR-PIB feedstock, PIB Mn 950-2300 selection, treat rate by service, and Indian sourcing.
| Architecture | PIBSA : PAM Ratio | PIB Mn | Polar Head Function | Best Service |
|---|---|---|---|---|
| Mono-succinimide | 1 : 1 | 950-1300 | Strong exposed amine — aggressive soot binding | Heavy-soot HDD top-treat |
| Bis-succinimide | 2 : 1 | 1300-2000 | Polyamine sandwiched between 2 PIB tails — balanced | PCMO & HDD workhorse |
| Tris-succinimide | 3 : 1 | 1600-2300 | 3 PIB tails per polyamine — very high viscosity contribution | Gear oil & specialty |
| Borated bis-succinimide | 2 : 1 + B | 1300-2000 | B-N modification — FKM seal-friendly + chain wear | GF-6 / GF-7 PCMO |
| Ethylene-carbonate cap | 2 : 1 + EC | 1300-2000 | Capped amine — reduced basicity, low-temp friendly | Low-SAPS C3 PCMO |
| Mannich-base (alternative) | Phenol + CH2O + PAM | 1600-2300 | Phenol-amine linkage — high thermal stability | Specialty / legacy |
| PIB Mn | Service | Why This Mn |
|---|---|---|
| 950 | PCMO low-soot, low-viscosity 0W-16 / 0W-20 | Low MW gives low viscosity contribution — doesn't push KV100 over target |
| 1300 | PCMO API SP / GF-6 workhorse 5W-30 / 5W-40 | Sweet spot — good dispersancy, manageable viscosity |
| 1600 | HDD CJ-4 / mid-soot HDD | Better soot suspension than 1300, still oil-soluble |
| 2000 | HDD CK-4 with HR-PIB — heavy soot | High Mn for heavy-soot HDD; HR-PIB needed for chlorine-free |
| 2300 | Off-road / construction HDD, marine | Maximum soot suspension; viscosity contribution accepted |
| Service | Dispersant Type | Treat % (finished) | Nitrogen ppm (finished) |
|---|---|---|---|
| PCMO API SP / GF-6 | Bis + borated (90:10) | 3-5% | 450-750 |
| PCMO ACEA C3 low-SAPS | Bis + EC-capped | 4-6% | 600-900 |
| HDD API CK-4 | Bis Mn 2000 HR-PIB | 6-9% | 900-1350 |
| HDD API CI-4+ (legacy) | Bis Mn 2000 + mono top-treat | 7-10% | 1050-1500 |
| Marine System Oil | Bis Mn 1600 | 3-5% | 450-750 |
| Off-road / Construction HDD | Bis Mn 2300 | 7-9% | 1050-1350 |
| Motorcycle JASO MA2 | Bis Mn 1300 | 3-4% | 450-600 |
Bis-succinimide (PIBSA:PAM = 2:1) is the workhorse for PCMO and most HDD. The bis architecture has the polar polyamine head sandwiched between two PIB tails — better oil solubility, lower polarity at the head and more controlled dispersancy.
Mono-succinimide (PIBSA:PAM = 1:1) has more exposed amine groups — stronger polar interaction with soot and sludge but worse cold-temperature performance. Used in heavy-soot HDD or as top-treat. Tris-succinimide (3:1) is rare — used for very-high-viscosity-thickening dispersancy in specific gear oil grades.
Borated succinimide is bis-succinimide post-treated with boric acid to incorporate 0.5-2.5% B into the polyamine head. Three benefits: (1) Fluoro-elastomer (FKM) seal compatibility — boron neutralises the amine reactivity that attacks FKM seals; (2) Chain wear protection in ILSAC GF-6 / GF-7 — boron-modified tribofilm reduces engine chain elongation; (3) Improved soot handling at high concentration in HDD CK-4.
Borated dispersant treat rate 0.5-1.5% in finished oil, often as a partial substitute for plain bis-succinimide.
HR-PIB = High-Reactivity Polyisobutylene. Conventional PIB has ~10% terminal vinylidene (=CH2) bonds; HR-PIB has 80-90% terminal vinylidene. In the succinimide reaction (PIB + maleic anhydride → PIBSA), the terminal vinylidene reacts cleanly via the ene mechanism without needing chlorine catalyst.
HR-PIB gives higher PIBSA yield, lower residual maleic anhydride and a chlorine-free product. Conventional PIB requires Cl-route via PIB chlorination + maleic anhydride — gives ~50-300 ppm residual chlorine in the dispersant. Modern OEM-spec PCMO often requires HR-PIB.
For HDD soot-handling dispersancy, PIB Mn 1300-1600 is the sweet spot. Lower Mn (950-1300) for PCMO sludge dispersancy where lower viscosity and lower polarity helps cold-start. Higher Mn (2000-2300) for HDD CK-4 / CJ-4 with very heavy soot loading and for marine applications.
Mn 1300 bis-succinimide is the workhorse PCMO API SP DI ingredient. Mn 2000 bis-succinimide with HR-PIB is the typical HDD CK-4 dispersant for soot suspension at end-of-drain.
PCMO API SP — 3-5% dispersant in finished oil. ACEA C3 low-SAPS PCMO — 4-6% (more dispersant needed because lower detergent TBN). HDD CK-4 — 6-9% (heavy soot suspension). HDD CI-4+ — 7-10% (legacy high-soot). Marine system oil — 3-5%. Off-road / construction HDD — 7-9%. Motorcycle 4T JASO MA2 — 3-4% (lower than PCMO because less sludge from short trips and lower oil capacity).
Mannich-base dispersants are made by Mannich condensation of alkylphenol + formaldehyde + polyamine. Older chemistry, gives slightly better thermal stability than succinimide but uses formaldehyde (regulatory issue, NPE alkylphenol issue) and contributes phenolic odour.
Largely replaced by PIBSA-PAM succinimide for new formulations. Some niche industrial gear oil and specialty hydraulic still use Mannich dispersants — they are also better at very high temperature (>180 °C) where succinimide can decompose.
Branded from Lubrizol (LZ 6418, 6420), Afton HiTEC (657, 645), Infineum (C9268, C9275), Chevron Oronite (OLOA 219), BASF Sokalan / Glissopal (PIB feedstock + dispersant), Croda. Branded lands at ₹380-480 / kg.
Indian-blended from Lubechem custom equivalent (LC-DSP-PIBSA-BIS, LC-DSP-BTR borated) lands at ₹240-310 / kg — 32-37% saving. PIB feedstock from BASF Glissopal (Mumbai distribution), Lubrizol Indopol, INEOS Indopol.
Two-stage process control. Stage 1 — PIBSA formation: PIB + maleic anhydride at 200-220 °C (ene route, HR-PIB) or PIB chlorination + maleic anhydride at 200 °C (Cl-route, conventional PIB). Saponification number (SAP) and free maleic anhydride monitored.
Stage 2 — succinimide formation: PIBSA + polyamine (TEPA, PAM, HPA) at 150-180 °C with water of condensation removed by N2 sparge / vacuum. Final QC: total base number, nitrogen content by Kjeldahl, residual chlorine (Cl-route), viscosity, foam, storage stability.
Share your target architecture (mono / bis / borated), PIB Mn requirement, service category and volume. We respond within one business day with a process plan and indicative cost.