Overview
ZDDP (zinc dialkyldithiophosphate) is a multifunctional additive providing anti-wear, antioxidant, and corrosion-inhibiting properties. It forms a protective tribofilm on metal surfaces under boundary lubrication conditions, and reacts with peroxy radicals to interrupt the oxidative chain. The alkyl structure, primary, secondary, long-chain, or aryl, determines the balance between thermal stability, anti-wear activity, and phosphorus volatility. Zinc and phosphorus content are the key specification parameters. ZDDP remains the cornerstone anti-wear additive in engine oils, hydraulic fluids, and gear oils.
| Chemistry | Zn % | P % |
|---|---|---|
| Zinc Butyl Octyl Primary Alkyl Dithiophosphate | 8.5–10.0 | 7.2–8.5 |
| Zinc Primary Alkyl Dithiophosphate | 9.2–9.8 | 8.3–8.7 |
| Zinc Dioctyl Primary Alkyl Dithiophosphate | 8.5–10.5 | 7.5–8.8 |
| Zinc Primary-secondary Alkyl Dithiophosphate | 8.9–9.5 | 7.95–8.75 |
| Zinc Primary-Secondary Alkyl Dithiophosphate | 8.4–9.2 | 7.7–8.3 |
| Zinc Secondary Alkyl Dithiophosphate | 8.45–9.55 | 7.7–8.7 |
| Zinc Long-chain Alkyl Dithiophosphate | 6.2–7.6 | 5.6–6.6 |
| Zinc Primary Alkyl Dithiophosphate (Multi-functional) | 8.5–9.5 | 7.6–8.4 |
| Zinc Secondary Alkyl Dithiophosphate | 8.85–9.65 | 8.10–8.90 |
| Zinc Secondary Alkyl Dithiophosphate | 7.28–8.72 | 7.05–7.80 |
| Zinc Aryl Dithiophosphate | 2.8–3.8 | 2.55–3.15 |
| Zinc Dialkyl Dithiophosphate | 10.0–11.2 | 9.2–9.9 |
| Alkali-type Zinc Dioctyl Primary Alkyl Dithiophosphate | 8.7–9.5 | 7.0–7.7 |
| Zinc Propyl Octyl Secondary-Primary Alkyl Dithiophosphate | 9.5–10.3 | 8.5–9.3 |