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Lubricant Oil for Cummins Diesel Generator Set

Oct. 10, 2018

The function of Cummins Diesel engine Oil/lubricant oil


What kind of function does the engine oil of Cummins generator set have in the operation of the generator set? This article will give you a detailed introduction.

Lubricant Oil for Cummins Diesel Generator Set.jpg


1. Lubricating


The primary function of Cummins generator oil is to lubricate the moving parts. Oil forms a hydraulic oil film between metal surfaces to avoid direct contact between metal components and reduce friction. When the oil film is insufficient to avoid direct contact with metal components, the following situations will occur.


Friction produces heat

Produce partial bonding

Metal transfer resulting in bruising or sticking

Extreme pressure wear control


Modern lubricants include extreme pressure (EP) anti-wear additives. When the load of the prats is too high to form a hydraulic oil film, these additives form a chemically bonded molecular oil film on the metal surface at high pressure to avoid direct contact and wear. Oil scour contaminants on important parts and act as engine cleaners. If engine oil does not play a controlling role, piston rings, valve rods and oil seals on the sludge, paint film and oxide accumulation will cause serious damage to the engine. The oil with the best additives will keep the contaminants suspended until the oil filtration system filters or removes the contaminants during the oil exchange.


2. Protection

Oil provides protective barriers against non-similar metals to prevent corrosion. Corrosion, like wear, can cause metal debris to fall off the engine parts. Abrasion is like a slow wear process.


3. Cooling

The engine needs to cool the internal parts, and the main cooling system does not provide such cooling. Oil is an excellent heat conduction medium. Oil is an excellent heat conduction medium. Heat is transferred to the engine oil through contact with different parts and then to the main cooling system in the mooring cooler.


4. Seal


The engine oil fills the uneven surface of the cylinder liner, piston, valve rod and other internal parts of the engine, acting as combustion gas seal.


5. Hydraulic action


Engine oil also works as a hydraulic medium on the engine, typical applications such as Jacobo brakes and STC injectors. Additive oil system relies on additives to resist special contaminants during their active life. The effect of oil additive on the overall performance of engine is more important than oil itself. Without oil additives, even the highest quality engine oil can not meet the requirements of the engine.


Additives include:

1. Detergent or dispersant to keep insoluble substances suspended until oil is changed. The oil filtration system cannot filter out these suspensions. Excessive oil exchange intervals will result in sediment formation in the engine.


2. Inhibitors, maintain oil stability, avoid acid corrosion metal surface, and avoid engine when not running rust.


3. Other oil additives help lubricate the engine's high-load areas (such as valves and injector systems), prevent scratches and entrapment, control foam formation, and prevent air from remaining in the engine oil. Engine oil must be proportioned in such a way that the engine oil is not foamed by mechanical agitation processes associated with a lot of engine oil. Foaming oil can cause engine damage similar to damage caused by insufficient oil due to inadequate oil film protection.


Oil replacement cycle of Cummins Diesel Generator set


When is the best time to change oil for Cummins diesel generator? First, Cummins engine oil replacement technical specifications are based on the working cycle and oil pollution. This pollution occurs in all engines to varying degrees and regardless of design.


Oil pollution is the direct result of the normal operation of the engine. Load factor, fuel and environmental conditions will affect the speed of oil pollution. Laboratory and field tests confirm that the total amount of fuel consumed by the engine is proportional to the level of pollution prior to reaching the limits at which the engine oil can be absorbed and can still function according to the design requirements. Oil can absorb contaminants and still function according to design requirements before exceeding the pollution limit of oil. The relationship between oil consumption and oil pollution forms the basis for determining oil exchange intervals.


Prolonging the oil and filter replacement period will reduce engine life due to corrosion, carbon deposition, wear and other factors. Cummins' technical specifications for oil replacement are based on working cycles and oil contamination. This pollution occurs in all engines to varying degrees and regardless of design.


Table 3


Oil Exchange Index


Experimental Method





Kinetic viscosity (100.C) rate of change

More than ±1 SAE viscosity grade or higher 5cSt than new oil


Fuel dilution rate


Total base value (TBN)

Minimum 2.5 units, or half of new oil value, or equivalent to total acid value (TAN)

ASTM D-4739

Shuifen (CV 9)

Maximum 0.50 / 0


SOOT% not exceeding








Oil Exchange Index




latent pollutant 

Silicon (Si)

Increase 15ppm compared with new oil

sodium (Na)

Increase 20ppm compared with new oil

Boron (B)

Increase 25ppm compared with new oil

Potassium (K)

Increase 20ppm compared with new oil


1. Physical and chemical test method.


This technique involves comparing the analytical data of used oils with those obtained from the new state of oil. The degree of degradation of used oil relative to the new state provides the indicators required for the monitoring system. The main characteristics of oil that can be used as warning signals are pollution levels (oil, soot, silicon, boron, sodium, potassium) and generator oil viscosity and flash point. General pollution inspection criteria are set out in Table 3.


2. Load rate method

Typical for Mll vehicle engine. According to fuel consumption, gross vehicle weight, idle time and fuel type to determine the fuel exchange period. For more details, please refer to the Mll engine usage and maintenance Manual.


3. Graphology

The NT,K19 and K38 engines can determine the longest oil exchange cycle according to the "oil change interval curve" in the maintenance instructions or adopt the oil exchange cycle recommended in the table in Section 1, paragraph 3.


Above are information of Cummins generator lubricant oil maintenance. 

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