Overview
Ashless dispersants are high-molecular-weight polymeric additives that keep insoluble contaminants, combustion soot, oxidation products, wear particles, and water, suspended in the oil, preventing them from agglomerating into sludge or varnish deposits. Polyisobutylene succinimide (PIBSI) dispersants are the industry standard, available in mono- and bi-succinimide structures, with borated variants offering enhanced seal compatibility and antioxidant benefits. Nitrogen content and viscosity are key selection parameters.
| Chemistry | N % | KV @100°C (mm²/s) |
|---|---|---|
| High Nitrogen Polyisobutylene Bi-Succinimide | 1.7–2.1 | 450–650 |
| Polyisobutylene Mono-Succinimide | 2.0–2.5 | 140–270 |
| High Nitrogen Polyisobutylene Mono-Succinimide | 2.9–3.5 | — |
| Polyisobutylene Bi-Succinimide | 1.1–1.4 | 130–230 |
| Borated Polyisobutylene Succinimide | 1.1–1.4 | 130–250 |
| Borated Polyisobutylene Succinimide (High MW) | 1.3–1.6 | 300–500 |
| High MW Polyisobutylene Succinimide | 1.0–1.3 | 300–500 |