A Guide to Diesel Generator Set Engine Oil Change

In the routine maintenance of diesel generator sets, engine oil plays a crucial role. It is akin to the "lifeblood" of the generator set, directly affecting the engine's operational condition and, in turn, the overall performance and lifespan of the unit. Selecting the appropriate type of oil and changing it regularly can significantly enhance the performance and stability of the diesel generator. However, many users have numerous questions regarding oil changes, such as whether blackened oil necessarily means it needs to be replaced. This article will provide detailed answers to these questions, offering you a clearer understanding of diesel generator set oil maintenance.

Engine oil, also known as lubricating oil, is indispensable for the engine. Inside the engine, there are many metal surfaces that move and rub against each other. High-quality lubricating oil can effectively reduce the wear between these components, thereby extending the engine's lifespan. The primary functions of engine oil can be summarized as follows:

The most fundamental function of engine oil is to lubricate the various interacting surfaces within the engine, reducing friction between parts and ensuring smoother engine operation.

During operation, the engine generates a significant amount of heat. Engine oil helps dissipate some of this heat, providing a cooling effect and preventing the engine from overheating.

Engine oil can clean contaminants from engine parts, such as carbon deposits, sludge, and wear metal particles. It maintains the cleanliness of the engine's interior, preventing these contaminants from causing damage.

Engine oil can seal the gaps between the piston rings and the pistons, preventing gas leakage and enhancing the engine's sealing performance to ensure proper operation.

By adhering to metal surfaces, engine oil can effectively prevent rust and corrosion, protecting the internal engine components from damage.

Engine oil is primarily composed of base oil and additives. Base oil is the main component of lubricating oil, determining its fundamental properties. Additives, on the other hand, can compensate for and improve the deficiencies in the base oil's performance, endowing the lubricating oil with new characteristics. They are an essential part of the lubricant. The main types of additives include detergents, dispersants, antioxidants, anti-wear agents, oiliness agents, and friction modifiers.

Many users of diesel generator sets believe that once the engine oil turns black, it has deteriorated and needs to be replaced. However, this is not entirely correct. High-quality branded engine oils available on the market today can maintain their lubricating functions even under high-temperature conditions. Generally, when new oil is added, the sludge and carbon deposits on the engine parts will disperse into the oil. After a certain period, the oil will turn black. Therefore, blackened oil does not necessarily mean it has deteriorated and needs to be replaced. Before deciding to change the oil, it is important to identify the cause of the blackening.

The oil change interval is a very important issue. Generally, new generator sets should have their oil changed after the first 50 hours of operation and again after 50 hours following medium or major repairs. The oil change interval is usually synchronized with the oil filter (element) change, typically every 250 hours or one month. However, it is important to note that if the oil exceeds its effective period, it should be changed even if the change interval has not been reached. Additionally, if the diesel generator set operates in harsh environments for extended periods, the oil change interval should be shortened, as such conditions can accelerate the wear of internal components.

When changing the oil in a diesel generator set, users should follow the manual's recommendations and select the appropriate type of oil based on the local season and temperature. Do not blindly pursue high-priced oils to avoid unnecessary waste. Generator oil is an essential lubricant for the normal operation of the engine. It not only reduces friction and wear between internal engine parts but also maintains engine cleanliness. The oil change interval is generally synchronized with the oil filter (element) change, with regular oil typically requiring a change every three months. For synthetic oil, it is recommended to change it every six or nine months.

To accurately determine the oil change time for a diesel generator set, the following two methods can be used:

Prepare two glass test tubes with a diameter of 0.5 cm and a length of 20 cm. Fill each tube with 19 cm of new and used oil, respectively. Seal the tubes and invert them simultaneously, then record the time it takes for the bubbles to rise. If the difference exceeds 20%, it indicates that the viscosity of the used oil has decreased significantly and it should be replaced.

Drop new and used oil onto a white filter paper for comparison. If the used oil drop contains many black spots, it indicates that the oil has not deteriorated and does not need to be replaced. If the oil appears dark brown, it has deteriorated and should be replaced.

Under normal circumstances, diesel generators should have their oil changed after every 500 hours of operation. However, in actual use, sometimes the oil becomes thin and contaminated with impurities before the scheduled change time, rendering it unusable. The main reasons for rapid oil deterioration are as follows:

If the selected oil grade does not meet the engine's requirements or if the oil quality itself is substandard, it can lead to rapid oil deterioration.

When exhaust gas enters the oil pan, it condenses into water and acidic substances, which can cause the oil to deteriorate.

If the diesel generator set has issues such as gas leakage, oil leakage, excessive clearance, or high oil temperature, it can lead to oil deterioration.

If the diesel generator set frequently operates at low temperatures, low loads, and low speeds, the piston deformation is insufficient, combustion is incomplete, and diesel fuel can seep down the cylinder walls into the oil pan, causing the oil to thin and deteriorate.

A damaged filter element sealing ring can cause internal leakage, allowing some of the oil to bypass the filter element and pass directly through the filter, leading to oil deterioration.

If the oil filter element is excessively dirty, unfiltered dirty oil enters the lubrication system, not only accelerating the wear of the diesel generator set's parts but also causing the oil to deteriorate.

Changing the oil in a diesel generator set is an important maintenance task. The correct method of changing oil can ensure the normal operation of the engine. Here are the specific steps for changing the oil:

Place the generator set on a flat surface and start the engine for a few minutes to warm up the oil, then stop the engine. Remove the drain plug (i.e., the oil dipstick). Place an oil pan under the engine to collect the drained oil.

Remove the drain plug, and the oil will drain from the crankcase. During the draining process, inspect the drain plug, gasket, and rubber ring. If any are damaged, replace them immediately. Reinstall and tighten the drain plug.

Fill the oil to the upper part of the mesh grid on the oil dipstick. After changing the oil in the diesel generator, ensure that the oil level is between the minimum and maximum marks. Check the oil level every 8 hours during continuous use.

Run the engine to operating temperature. Remove the drain plug from the oil pan and drain the lubricating oil. Install a new gasket on the bottom plug. Remove the full-flow and bypass filters, ensuring that no gaskets are left on the engine. Clean the filter mounting surface to prevent dirt from entering the engine when installing the new filter. Do not pre-fill the filter with lubricating oil (as the oil will bypass the filter and contaminate the lubrication system). Apply some lubricating oil to the gasket, hand-tighten the filter onto the engine until the gasket contacts the base, and then tighten it an additional 3/4 turn.

Add the lubricating oil to the appropriate level, not exceeding the maximum mark. Start the engine and let it idle to check if the oil pressure is normal. Turn off the engine and inspect for any oil leaks around the filter. Add more oil if necessary.

Engine oil plays a vital role in the maintenance of diesel generator sets. Choosing the right type of oil and changing it regularly can effectively extend the engine's lifespan and improve the performance and stability of the generator set. Users should determine the oil change interval based on actual conditions and avoid blindly pursuing high-priced oils. It is also important to be aware of the causes of oil deterioration to prevent rapid oil degradation due to improper operation or harsh environments. The correct method of changing oil can ensure the normal operation of the engine and the stable running of the diesel generator set. We hope that this article has helped you gain a better understanding of diesel generator set oil maintenance and provided valuable knowledge to ensure the smooth operation of your equipment.