Firstly, we need to understand that the oil used in diesel generator sets of different manufacturers and powers is different. Generally, a new engine operates for 50 hours after the first operation and 50 hours after medium or major repairs. The oil change cycle is usually carried out simultaneously with the oil filter (element), and the oil change cycle is generally 250 hours or one month. Using type 2 engine oil, the oil can be extended for 400 hours before being replaced, but the oil filter (filter element) must be replaced.

1. Using two glass test tubes with a diameter of 0.5 centimeters and a length of 20 centimeters, fill them with 19 centimeters of new engine oil and used engine oil respectively. After sealing, invert both tubes simultaneously and record the time when the bubbles rise. If the difference between the two exceeds 20%, it indicates that the viscosity of the used engine oil has decreased too much and should be replaced.

2. Compare the new and used engine oil by dropping one drop each onto a white filter paper. If there are many black spots in the used oil droplets, it indicates that the engine oil has not deteriorated and should not be replaced; If the engine oil is black brown, it indicates deterioration and should be replaced.