Proper Use of Hydraulic Oil

The correct use of hydraulic oil centers on four key aspects: selecting the right oil, preventing contamination, controlling temperature, and performing regular maintenance. Neglecting any of these areas can lead to system wear, malfunctions, or even premature equipment failure. The following insights are provided by the team at Jianlong Hydraulic Technology—feel free to reach out with any questions!

1. Oil Selection and Filling

Selecting the appropriate oil is the first step; you must strictly adhere to the grade specified in the equipment’s "User Manual." Never mix different grades of hydraulic oil, as this can trigger chemical reactions that degrade performance. Before filling, it is best to allow the new oil to settle and then pass it through a filter (typically with a rating of 5–10μm) rather than pouring it directly into the reservoir. Always clean the area around the reservoir filler port before adding oil to prevent dust or debris from entering.

2. Strict Contamination Prevention

Most hydraulic system failures stem from contamination. Moisture and impurities are the primary culprits: moisture can enter through cooler leaks or condensation from the air, while impurities may be introduced via piston rods, reservoir breather vents, or during maintenance. Ensure the reservoir cap remains tightly sealed, and regularly inspect, clean, or replace filters. If the oil turns dark brown, becomes milky white, or develops an unusual odor, it has degraded and must be replaced immediately.

3. Temperature Control and Air Bleeding

Excessive oil temperature accelerates oxidation and degradation; generally, the temperature inside the reservoir should not exceed 60°C. Conversely, if the oil temperature is too low (e.g., below 20°C), its fluidity will be poor—in such cases, preheat the oil to above 30°C or run the system under no-load conditions to raise the temperature before operation. Air trapped in the system can cause erratic movement, noise, and oil emulsification. After adding or changing oil, bleed out any trapped air using the air-bleed valves located at the top of the hydraulic cylinders, or by cycling the cylinders back and forth several times.

4. Regular Inspection and Replacement

Monitor oil levels and quality on a routine basis. The oil level should remain within the range indicated on the dipstick or sight gauge; top up with the same grade of oil if necessary. When changing the oil, thoroughly clean the reservoir and drain all old oil to prevent the mixing of old and new fluid. Even with infrequent use, it is generally not recommended to continue using hydraulic oil that has been stored or in service for more than 24 months.

Important Note: If any abnormalities are detected in the hydraulic oil—regardless of how long it has been in use—it should be replaced immediately. Furthermore, the root cause of any contamination or degradation must be investigated, rather than simply performing an oil change. Please contact us for further consultation or inquiries regarding hydraulic oil. Jianlong Hydraulic Technology specializes in the custom design and manufacture of 100–5,000-ton frame-type hydraulic presses. We possess mature technology and extensive experience, with capabilities that include the integration of automated production lines, chillers, air compressors, and other auxiliary equipment. All our hydraulic presses are CE-certified and fully compliant with the EU Machinery Directive (2006/42/EC). Our products are exported to markets across Europe and the Americas, including Germany, the United States, Mexico, and Portugal. Should you have any questions or procurement requirements, please reach out to us (you may also scan the WhatsApp QR code below). Jianlong Hydraulic Technology is dedicated to providing you with personalized, customized, and professional solutions—we look forward to serving you.