Storage tank facilitating long-term storage of lubricating oil

The utility model relates to a storage tank easy for long-term storage of lubricating oil, which comprises a tank body, an oil storage cavity is arranged in the tank body, an oil filling pipe is arranged at the top of the tank body and communicated with the oil storage cavity, a filter screen is fixed on the inner wall of the oil filling pipe and matched with the cross section of the oil filling pipe in shape, and an oil outlet pipe is arranged on a cylinder body of the tank body and communicated with the oil storage cavity. The bottom of the tank body is provided with a drain pipe, the drain pipe is communicated with the oil storage cavity, the drain pipe is connected with a valve, the drain pipe is used for discharging water on the lower portion after standing from the oil storage cavity, an observation opening is formed in the side, close to the drain pipe, of a cylinder body of the tank body, an observation plate is embedded and fixed in the observation opening, and an openable turning plate is arranged a