Info Centre >> Fuel and Lube Oil Technical Manual >> 7. Lube Oil - Test Results >> 7.2 Diesel Engine Oil
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Diesel engine oils - Lubricants & Additives
Diesel engine oils are complex to analyse and interpret. The oils are required to manage large amounts of internal contaminants, including combustion products and water.
Diesel Engine Oil Lubricants
Lubricants have several functions in an engine. They:
The lubricant is expected to continue to perform these functions throughout the useful lifetime of the oil charge. Modern engines with low oil consumption increase these performance demands. Oil consumption enables a system to receive fresh oil replenishments that help to restore some of the basic properties. This, plus the effects of associated oil centrifuging equipment, usually creates equilibrium conditions within the system.
Diesel Engine Oil Additives
The additives in the oil are initially capable of providing protection against the high temperatures and corrosive atmospheres that are present in the modern internal combustion engine. However, over time and constant assault, the additives and oil gradually deteriorate. Soot, wear metals and fuel contamination all contribute to oxidative breakdown, slowly destroying the lubricating properties of the engine oil, while the alkaline detergent additive is depleted by the formation of strong acids from combustion of the fuel.
| Diesel Engine Oil | |||||||||||||||||||
Type |
Fuel |
Viscosity |
Insolubles |
TBN |
Water |
Flash Point |
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| Change | Maximum | Change/Min | Maximum | Minimum | |||||||||||||||
| Automotive | Distillate | + / - 25% | 2% | -60% /1 | 0.5% | 180° | |||||||||||||
| High Speed | Distillate | + / - 20% | 2% | -50% /2 | 0.3% | 180° | |||||||||||||
| Medium Speed | Distillate | +20% -10% | 2.5% | -50% /5 | 0.2% | 180° | |||||||||||||
| Medium Speed | Residual | +20% -10% | 2.5% | -50% /10 | 0.2% | 180° | |||||||||||||
| Slow Speed | Residual | +30% -10% | 1% | +50% /12 max. | 0.2% | 180° | |||||||||||||
