Situations & Risks of Mixing Engine Oils in Diesel Generators

 
Diesel generators are high-precision power generation devices, and selecting the right engine oil is crucial for their operation. Engine oil is key to ensuring the efficient and stable running of the generator. It performs multiple functions including lubrication, friction reduction, heat dissipation, sealing, vibration damping, and rust prevention, playing an irreplaceable role in the daily operation of diesel generators. However, many users often question whether it is acceptable to mix new and used engine oil, different brands, or even oils with varying viscosities. This article will explore this issue in detail and analyze the potential risks associated with mixing engine oils.

Risks of Mixing New and Used Engine Oil

 
Many users, aiming to cut costs or for other reasons, mix new and used engine oil. However, this practice not only fails to reduce maintenance costs but may also severely impact the diesel generator. Used engine oil contains a significant amount of oxidized materials. When mixed with new oil, these oxidized substances can accelerate the oxidation of the new oil, thereby shortening its lifespan and greatly diminishing its lubricating effect.
 
Tests have shown that when using entirely new oil, the oil's lifespan can reach around 1500 hours. However, if a mixture of equal parts new and used oil is used, the oil's lifespan is reduced to just 200 hours, decreasing by more than 7 times. This not only increases maintenance frequency and costs but can also lead to equipment failure, affecting the generator's normal operation.

Differences in Oil Formulations

 
Although both diesel and gasoline engines rely on oil for lubrication and protection, their working environments and requirements are significantly different.

1. Operating Conditions

 
Diesel engines have a compression ratio typically more than double that of gasoline engines, with a high-temperature and high-pressure environment that far exceeds that of gasoline engines. Diesel engines require oils with higher temperature and wear resistance, whereas gasoline engines operate under relatively lower temperatures and pressures.

2. Different Additives

 
Diesel engine oils generally contain more anti-corrosion additives. These additives form a protective layer on bearings and key components, reducing corrosion and enhancing wear resistance. Gasoline engine oils, on the other hand, do not provide the same level of protection. Using gasoline engine oil in a diesel engine, due to the harsh operating conditions, leads to the rapid failure of the oil's additives, resulting in increased wear and potentially severe engine issues.
 
Thus, the formulations of diesel and gasoline engine oils are designed for different operating conditions, and mixing them is not recommended as it can impair engine performance.

Impact of Mixing Different Brands of Oil

 
Even when using oils of the same type and viscosity, mixing different brands can still pose risks. Each brand's oil formulation includes different base oils and additives, which may react chemically when mixed. This can lead to a reduction in oil performance, and in some cases, the formation of acidic or alkaline compounds that accelerate component corrosion.
 
Additionally, mixing oils from different brands may lead to abnormal exhaust emissions. The mixed oil's reduced lubricating effect might cause oil to burn in the cylinders, producing blue smoke, while poor cylinder sealing can result in black smoke from the exhaust. These emission issues not only affect engine performance but can also lead to environmental pollution.

Other Risks of Oil Mixing

 
Aside from the issues mentioned, mixing engine oils can introduce several other risks that affect both oil performance and long-term engine maintenance. 

1. Formation of Sludge

 
Mixing oils increases the risk of sludge formation. Sludge is a viscous substance composed of oil residues and contaminants that can accumulate inside the engine. It significantly reduces the oil's heat dissipation capabilities, leading to engine overheating and a series of issues such as reduced power and unstable performance.

2. Clogging of Filters and Oil Passages

 
The formation of sludge and other residues can clog filters and oil passages, obstructing the normal flow of oil. This blockage impairs lubrication, leading to increased wear on engine components and potential pump failures or other critical issues, disrupting engine operation.

3. Reduced Wear Protection

 
One of the most critical properties of engine oil is its wear protection. Mixing oils can disrupt the oil film structure, leading to a significant reduction in wear protection. A compromised oil film increases friction between pistons and cylinder walls, potentially causing piston ring breakage or other mechanical damage. This not only raises repair costs but can also shorten engine lifespan.
 
In summary, diesel generators, being precision machinery, have high demands for engine oil. Mixing new and used oils, or oils of different brands and types, should be avoided. Such practices can shorten oil lifespan, reduce lubrication effectiveness, increase component wear, and even lead to serious mechanical failures. To ensure the proper operation and extend the lifespan of diesel generators, users should strictly follow equipment requirements, choose suitable diesel engine oils, and perform regular oil changes to avoid unnecessary faults and damage caused by oil mixing.