Hydraulic Oil Guide for SOOSAN Breaker Operators

Hydraulic oil is the lifeblood of your SOOSAN hydraulic breaker system. The wrong oil grade, contaminated fluid, or overdue oil changes are among the most common causes of premature hydraulic component failure — and the most preventable.

This guide covers everything operators and fleet managers need to know about hydraulic oil selection, contamination prevention, and change intervals for SOOSAN SB and SQ series breakers.

In a hydraulic breaker system, the oil serves four critical functions:

1. Power transmission — transfers energy from the excavator's hydraulic pump to the breaker's piston
2. Lubrication — reduces friction and wear on internal components including the piston, cylinder, and valve
3. Heat dissipation — carries heat away from high-temperature components
4. Contamination control — suspends and carries particles to the filter for removal

When the oil degrades or becomes contaminated, all four functions are compromised simultaneously.

SOOSAN hydraulic breakers are designed to operate with hydraulic oil in the following viscosity range:

Most operators in moderate climates should use ISO VG 46 — this is the standard grade for most excavator hydraulic systems.

Use hydraulic oil meeting the following minimum specifications:

• ISO 11158 HM grade (anti-wear hydraulic oil)
• DIN 51524 Part 2 HLP (European standard)
• Viscosity Index (VI): Minimum 95
• Anti-wear additives: Required (zinc-based ZDDP or ashless)
• Anti-foam additives: Required
• Rust and oxidation inhibitors: Required

Do not use: Engine oil, gear oil, transmission fluid, or hydraulic oil without anti-wear additives in a hydraulic breaker system.

The following brands meet SOOSAN's hydraulic oil requirements (ISO VG 46 HM):

• Shell Tellus S2 M 46
• Mobil DTE 25
• Castrol Hyspin AWS 46
• Total Azolla ZS 46
• Chevron Rando HD 46

Always verify the specification on the product data sheet before use.

• Optimal: 40–60°C (104–140°F)
• Acceptable: 20–80°C (68–176°F)
• Maximum: 80°C (176°F) — stop operation if exceeded

If your hydraulic oil temperature consistently exceeds 70°C, investigate:

• Clogged hydraulic oil cooler — clean the cooler fins
• Low oil level — check and top up the reservoir
• Incorrect oil viscosity — too thick oil generates more heat
• Excessive back pressure — check return line restrictions
• Worn hydraulic pump — reduced efficiency generates heat
• Continuous breaker operation — allow cooling breaks every 1–2 hours

In cold climates, hydraulic oil becomes thick and flows poorly:

• Warm up the excavator for 10–15 minutes before operating the breaker
• Use lower viscosity oil (ISO VG 32) in sustained cold conditions
• Do not operate the breaker at full power until oil temperature reaches 20°C
• Consider hydraulic oil heaters for operations below -10°C

Contamination is the leading cause of hydraulic system failure. Understanding contamination types helps you prevent and detect problems early.

Particle contamination (most common)

• Source: Wear debris from components, external dirt ingestion, new oil contamination
• Effect: Abrasive wear on pump, valve, cylinder, and seals
• Detection: Oil appears dark or gritty; filter clogs frequently

Water contamination

• Source: Condensation, rain ingress, cooler leaks
• Effect: Corrosion, reduced lubrication, microbial growth, emulsification
• Detection: Oil appears milky or cloudy; water separates at bottom of sample

Air contamination

• Source: Low oil level, suction line leaks, foaming
• Effect: Cavitation damage, spongy controls, overheating
• Detection: Foamy oil, erratic breaker operation, noise

Chemical contamination

• Source: Wrong oil type mixed in, seal degradation products
• Effect: Seal swelling or hardening, varnish deposits, reduced lubrication
• Detection: Sludge in filter, sticky valves, seal leaks

At the reservoir:

• Keep the reservoir cap tight and sealed
• Use a breather filter on the reservoir vent
• Never leave the reservoir open during maintenance
• Use clean, sealed containers when adding oil

During maintenance:

• Clean all fittings before disconnecting hoses
• Cap open hydraulic lines immediately
• Use lint-free cloths only
• Filter new oil through a 10-micron filter before adding to the system

During operation:

• Inspect hose connections daily for leaks
• Replace damaged hoses immediately
• Monitor filter condition indicators

For high-utilization equipment, consider an oil analysis program:

• Take oil samples every 250–500 hours
• Send to a certified laboratory for analysis
• Results show particle count, water content, viscosity, and additive depletion
• Extend or shorten change intervals based on actual oil condition

Oil analysis typically costs $20–50 per sample and can save thousands in premature component replacement.

1. Warm the oil to operating temperature (40–50°C) — warm oil drains more completely
2. Position the machine on level ground
3. Shut down and depressurize the hydraulic system
4. Drain the reservoir completely — do not leave old oil in the system
5. Replace the hydraulic filter — always change the filter with the oil
6. Clean the reservoir interior with clean hydraulic oil (not solvent)
7. Fill with new oil — filter through a 10-micron filter during filling
8. Bleed air from the system by cycling controls slowly
9. Check for leaks after first operation
10. Record the change in your maintenance log

Check the hydraulic oil level daily:

• Check with the machine on level ground and the breaker lowered
• Oil level should be between MIN and MAX marks on the sight glass or dipstick
• Never overfill — overfilling causes foaming and seal damage
• Never operate below MIN — cavitation will damage the pump

Contact your service team or change the oil immediately if you observe:

• Milky or cloudy oil — water contamination
• Dark brown or black oil — severe oxidation or overheating
• Metallic particles in the oil or on the filter — component wear
• Burning smell from the hydraulic system
• Frequent filter clogging — excessive contamination
• Foamy oil — air ingestion or wrong oil type

Proper hydraulic oil management is one of the highest-return maintenance investments you can make. Clean, correctly specified oil at the right level keeps your SOOSAN breaker performing at full power and extends the life of every hydraulic component in the system.

For technical support or to order SOOSAN-approved hydraulic fluids and filters, contact our team at [email protected].