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SECTION - VI

SPECIFICATIONS FOR LUBRICANT, COOLANT AND FUEL

6.1 Lubricant

6.1.1 The functioning of lubricating oil in a diesel engine

The lubricating oil used in the engine must be multifunctional. It must perform

the primary functions of:

1. Lubrication: Basic function is to reduce friction and minimize the wear and

tear. The engine oil to form a lm between the moving parts (such as bearings,

pistons, piston rings, cylinder liners and the valve train) and ensure sufcient

lubrication between the moving parts.

2. Cooling : Acts as a media for high heat transfer (from combustion chamber) and

protecting the moving parts from overheating.

3. Detergency: Cleaning pistons and preventing sludge build-up on internal

surfaces

4. Prevention from corrosion: Corrosion prevention by neutralizing the acid and

protecting the components from atmospheric humidity by creating a layer.

5. Sealing: By lling in the uneven surfaces in the cylinder wall, valve stems and

turbocharger oil seals.

6.1.2 Engine oil consist of

Engine oil consists of base oil and additives. Base oil is the most basic raw materials

of engine oil and additives are added for enhancing the oil properties which is

suited for diesel engine applications. Basic additives are viscosity modiers, anti-wear

additives, detergents, dispersant and antioxidant etc.

6.1.3 Why oil to be drained?

Engine lubricating oil must be drained when it can no longer perform its functions in

an engine. Oil doesn’t wear out, but it becomes contaminated/ degraded to the point

that it can no longer satisfactorily protect the engine. The engine oil degradation is

a normal result of engine operation, where oil properties changed mainly because

of reaction to the combustion by products.

6.1.4 How engine oil performance getting deteriorated

1. By-products of Engine Combustion: Soot from partially burned fuel will

con-

taminate the fresh oil and over a period of time, viscosity of the oil will

increase.

2. Base (BN) additives become neutral due to reaction with acid, produced during

combustion process.

3. Varnish and sludge which are formed as a result of the oxidation of the oil as it

breaks down or decomposes which leads to oil thickening

WEICHAI WP12 User Manual

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