Shear Stability Tester for Polymer-Containing Oils
A Shear Stability Tester evaluates the viscosity stability of polymer-containing lubricants, such as multigrade engine oils, hydraulic fluids, and gear oils, when subjected to mechanical shear stress. This test determines how polymer-based lubricants resist breakdown under high-pressure conditions, which is essential for maintaining long-term viscosity performance.
Test Standards
✅ ASTM D2603 – Sonic Shear Stability of Hydraulic Fluids
✅ ASTM D5275 – Sonic Shear Stability of Transmission & Gear Oils
✅ ASTM D6278 – Shear Stability of Polymer-Containing Oils using a European Diesel Injector
✅ CEC L-14-A-93 – Shear Stability Test for Automatic Transmission Fluids (ATF)
Principle of the Test
The test simulates the mechanical stress that oil experiences in engines, gearboxes, and hydraulic systems by subjecting it to controlled shear forces. The primary goal is to measure the permanent viscosity loss caused by polymer breakdown.
🔹 Sonic Shear Method (ASTM D2603, ASTM D5275)
- Uses a high-frequency sonic oscillator to agitate the oil for a set time.
- Measures viscosity loss before and after exposure.
- Typically used for hydraulic fluids and low-viscosity oils.
🔹 Diesel Injector Shear Method (ASTM D6278, CEC L-14-A-93)
- The oil is passed through a high-pressure diesel injector multiple times.
- This method is widely used for engine oils and gear oils.
- Measures viscosity loss at 100°C after shear stress.
Key Applications
🔹 Engine Oils (Multigrade & High-Performance Oils)
✅ Ensures long-lasting viscosity for fuel efficiency and wear protection
✅ Prevents polymer breakdown in turbocharged and high-RPM engines
🔹 Hydraulic Fluids (Industrial & Aerospace)
✅ Verifies shear resistance for stable operation in heavy machinery
✅ Prevents viscosity loss in high-pressure hydraulic systems
🔹 Gear Oils (Transmission & Differential Lubricants)
✅ Ensures proper lubrication in manual and automatic transmissions
✅ Reduces polymer shear degradation in heavy-duty and off-road vehicles
🔹 Automatic Transmission Fluids (ATF)
✅ Evaluates shear stability for consistent shifting performance
✅ Prevents oil thinning under high-load, high-temperature conditions
Popular Shear Stability Testers
🔹 Tannas TBS 2100 – Injector Shear Stability Tester (ASTM D6278)
🔹 Koehler K91700 – Sonic Shear Stability Tester (ASTM D2603)
🔹 Anton Paar SVM Series – Viscosity measurement for post-shear analysis
🔹 CANNON Shear Stability Tester – Diesel Injector-based test system
Oil Types That Require Shear Stability Testing
Shear stability testing is essential for oils that contain polymer-based viscosity modifiers. These oils must resist mechanical breakdown under high stress to maintain proper lubrication and viscosity. Below are key oil types that undergo shear stability testing:
1. Engine Oils (Multigrade & High-Performance Oils)
🔹 Examples:
- SAE 5W-30, 10W-40, 15W-50, 0W-20 (Multigrade engine oils)
- Synthetic & Semi-Synthetic Engine Oils
🔹 Why It Matters:
✅ Viscosity Modifiers in multigrade oils can degrade under stress, causing thinning.
✅ Prevents wear and loss of lubrication in high-RPM and turbocharged engines.
✅ Ensures fuel efficiency & longevity in modern engines.
✅ Test Methods:
- ASTM D6278 – Diesel Injector Shear Stability
- CEC L-14-A-93 – Engine Oil Shear Stability
2. Hydraulic Fluids (Industrial, Aviation, and Mobile Equipment)
🔹 Examples:
- ISO VG 32, 46, 68, 100 (Industrial hydraulic oils)
- Aviation Hydraulic Fluids (MIL-H-5606, MIL-PRF-83282, MIL-PRF-87257)
- Fire-Resistant Hydraulic Fluids (HFDU, HFD-R)
🔹 Why It Matters:
✅ Prevents viscosity loss in high-pressure hydraulic systems.
✅ Maintains fluid performance & system efficiency in machinery and aircraft.
✅ Reduces pump wear & cavitation risks.
✅ Test Methods:
- ASTM D2603 – Sonic Shear Stability of Hydraulic Fluids
- ASTM D5275 – Shear Stability of Transmission Fluids
3. Gear Oils (Manual Transmission, Differential, and Industrial Gear Lubricants)
🔹 Examples:
- SAE 75W-90, 80W-140, 85W-140 (Automotive gear oils)
- GL-4, GL-5, MT-1 (Manual transmission and differential oils)
- Industrial Gear Oils (AGMA 9005-E02, ISO VG 150-680)
🔹 Why It Matters:
✅ Ensures proper lubrication in high-load, high-temperature environments.
✅ Prevents shear-induced viscosity loss in truck differentials and industrial gears.
✅ Reduces component wear & extends service life.
✅ Test Methods:
- CEC L-45-T-93 – Gear Oil Shear Stability Test
- ASTM D6278 – Diesel Injector Shear Test
4. Automatic & Continuously Variable Transmission Fluids (ATF & CVT Fluids)
🔹 Examples:
- DEXRON, MERCON, ZF-LIFEGUARD (ATF fluids)
- CVT Fluids (Nissan NS-2, Honda HCF-2, Toyota FE)
🔹 Why It Matters:
✅ Ensures consistent shifting & transmission protection.
✅ Prevents fluid thinning in high-shear areas of automatic transmissions.
✅ Reduces frictional losses for better fuel efficiency.
✅ Test Methods:
- CEC L-45-T-93 – Transmission Fluid Shear Stability
- ASTM D5275 – Sonic Shear Stability Test
5. Heavy-Duty Diesel Engine Oils (Truck & Off-Road Equipment Lubricants)
🔹 Examples:
- API CK-4, FA-4, CJ-4 (Diesel engine oils)
- SAE 10W-30, 15W-40, 5W-40
🔹 Why It Matters:
✅ Prevents oil thinning under extreme engine loads.
✅ Ensures long-lasting viscosity control in long-haul trucking & construction vehicles.
✅ Reduces wear in turbocharged diesel engines.
✅ Test Methods:
- ASTM D6278 – Diesel Injector Shear Stability
- CEC L-14-A-93 – Heavy-Duty Engine Oil Shear Test
Conclusion: Why Shear Stability Testing Is Critical
✔ Prevents premature oil breakdown – Ensures oils maintain their designed viscosity.
✔ Extends equipment lifespan – Protects engines, gears, transmissions, and hydraulics.
✔ Improves fuel efficiency – Reduces frictional losses caused by polymer breakdown.
✔ Meets industry standards – Essential for OEM approvals and lubricant performance certification.