Polyisobutylene succinimide (PIBSI) is the most widely used ashless dispersant in engine oils. Its job is to keep soot, sludge and oxidation products suspended in the oil so they cannot deposit on engine surfaces or clog filters. Nearly every modern gasoline and diesel engine oil contains PIBSI, making it one of the highest-volume lubricant additives in the world.
What Is PIBSI?
PIBSI is produced by reacting polyisobutylene succinic anhydride (PIBSA) with polyethylene polyamine. The molecule has two parts: a long oil-soluble PIB tail that anchors in the oil, and a polar amine head that attaches to soot and sludge particles, keeping them dispersed. Key grades from Shanghai Minglan Chemical:
| Grade | Type | Nitrogen (m%) | TBN (mgKOH/g) | Typical use |
|---|---|---|---|---|
| T151 | Single alkenyl | ≥ 2.0 | 50-65 | Gasoline and diesel engine oils |
| T154 | Bis (double) | 1.1-1.3 | 15-30 | High-performance engine oils |
| T157 | High nitrogen | ≥ 3.2 | 70-105 | Premium dispersant applications |
| T161 | High molecular weight | 1.0-1.2 | 20-30 | Heavy-duty diesel, soot control |
All grades are viscous transparent liquids, chlorine-free, tested per ASTM D5762 (nitrogen) and ASTM D2896 (TBN). See the polyisobutylene succinimide product page and the ashless dispersant range.
How PIBSI Protects Engines
- Soot dispersion: in diesel engines, soot particles are kept separate and suspended, preventing abrasive agglomeration that wears rings and bearings.
- Sludge and varnish control: PIBSI keeps low-temperature sludge and high-temperature carbon deposits from settling on engine parts.
- Synergy with detergents: PIBSI works with metal detergents and ZDDP – the dispersant suspends contaminants while the detergent neutralises acids.
Selection Guide
- Match the grade to your oil type: T154 bis-type for passenger car oils, T161 high-MW for heavy-duty diesel, T157 high-nitrogen where extra dispersancy is needed.
- Typical treat rate is 2.0-4.0% in the finished oil; verify in your base oil with the full package.
- Check compatibility with your detergent, ZDDP and antioxidant selection.
- For marine and natural gas applications, consider boronated PIBSI grades (T151B/T154B/T161B) for enhanced performance.
Source PIBSI From Minglan
Shanghai Minglan Chemical manufactures the complete PIBSI dispersant family – single, bis, high-nitrogen, high-molecular-weight and boronated grades – with in-house testing on every batch. Contact info@lubeadditive.com for samples, specifications and pricing.
