Hydraulic Oil Capacity and Maintenance for the Bobcat S220

[MikePhua]

Bobcat S220 Loader Overview
The Bobcat S220 skid steer loader was introduced in the early 2000s as part of Bobcat’s high-performance S-series. With a rated operating capacity of 2,200 lbs and a turbocharged diesel engine producing 75 hp, the S220 was designed for demanding tasks in construction, landscaping, and agriculture. Its hydraulic system powers the lift arms, tilt cylinders, auxiliary attachments, and drive motors, making fluid integrity critical to performance.
Bobcat, founded in North Dakota in 1947, became a global leader in compact equipment by pioneering the skid steer loader. The S220 was part of a generation that emphasized operator comfort, serviceability, and hydraulic versatility.
Hydraulic Oil Capacity and System Layout
The S220’s hydraulic system includes:

• Reservoir tank: Holds approximately 5 gallons of hydraulic fluid
  
• Hydraulic lines and cylinders: Add another 2–3 gallons depending on attachment configuration
  
• Drive motor filters: Require periodic inspection and may retain fluid during service
  
• Auxiliary circuit: Used for tools like augers or grapples, adds variable volume
  

For a full system drain and refill, operators should prepare 8–9 gallons of hydraulic oil to ensure complete replenishment. Always check the manual for exact specs based on serial number and configuration.
When to Replace Hydraulic Oil
Hydraulic oil should be replaced when:

• Contamination is suspected: Water ingress, metal particles, or sludge
  
• Machine has sat idle for extended periods: Moisture and oxidation degrade oil
  
• After major hydraulic failures: Broken hoses, leaking seals, or motor shaft damage
  
• Scheduled maintenance interval is reached: Typically every 1,000 hours or annually
  

One operator noted that while he rarely performed full oil changes, he often topped off the system due to hose failures, seal leaks, and coupler damage. In a busy season, he used 3–4 pails of oil just to maintain levels.
Filter Replacement and Inspection Points
The S220 includes:

• Two hydraulic filters: One inline and one at the drive motors
  
• Return line screen: Captures large debris before fluid re-enters the tank
  
• Sight glass or dipstick: Used to check fluid level and clarity
  

During service:

• Replace both filters
  
• Inspect hoses for abrasion or cracking
  
• Check couplers and fittings for bypass leakage
  
• Clean the reservoir cap and breather to prevent contamination
  

If the oil appears clean and the machine operates smoothly, some operators choose to replace only the filters and top off the fluid. This approach is acceptable for well-maintained machines but not recommended after contamination events.
Choosing the Right Hydraulic Oil
Bobcat recommends a premium hydraulic fluid meeting ISO 46 or ISO 68 viscosity standards, depending on climate. In colder regions, ISO 46 offers better flow at startup. In hot environments, ISO 68 provides better film strength.
Key properties to look for:

• Anti-wear additives
  
• Oxidation resistance
  
• Water separation capability
  
• Compatibility with seals and hoses
  

Avoid mixing brands or types unless compatibility is confirmed. Always flush the system if switching from mineral to synthetic fluids.
Conclusion
Maintaining the hydraulic system on a Bobcat S220 requires attention to fluid volume, filter integrity, and contamination risks. With a total system capacity of 8–9 gallons, operators should plan for full replacement during major service or after extended downtime. Regular filter changes and visual inspections can extend component life and prevent costly failures. In the world of compact loaders, clean hydraulic oil is the lifeblood of productivity.