Evaluation and Qualification of Gasoline and Diesel Engine Lubricants

Meeting the Future

For more than 65 years, lubricant, additive, and equipment manufacturers have been striving to improve automotive engine oil performance. Southwest Research Institute (SwRI) serves as a technical partner to help clients develop engine oils that meet modern engine requirements and future lubricant performance challenges.

Lubricants for spark-ignited engines are updated as the performance needs of new engines change and as new regulations, such as the 100,000-mile emissions durability requirement for passenger cars, are imposed. Lubricants must not only protect the engine, they must also be compatible with the exhaust oxygen sensor and catalyst. To help vehicle manufacturers meet corporate-average fuel economy standards, industry is developing advanced engine oils that improve fuel efficiency by reducing engine friction.

Diesel engine designs are evolving to meet future emissions and fuel economy requirements. New engines exhibit lower exhaust emissions and greater efficiencies as a result of improved combustion systems, design, and materials, although they challenge fuels, lubricants, and traditional engine oil test procedures.

Diesel Engine Lubricants

To ensure long engine service, lubricants are compared to a series of specifications, such as MIL-L-2104H and API service classifications CI-4 and CJ-4. SwRI analyzes lubricants through engine test procedures to determine factory fill, factory branding as genuine oils, and service fill. The Institute performs all recognized test procedures, including:

Mack T-8 Mack T-11 Mack T-12 Cummins ISM & ISB GM RFWT

Caterpillar IM-PC Caterpillar 1K Caterpillar 1N Caterpillar 1P Caterpillar 1R Caterpillar C13

SwRI has 38 test stands available for the diesel lubricant test procedures, which utilize engines representative of heavy-duty diesel engines operating in modern commercial fleets and off-highway applications.

SwRI simulates heavy-duty diesel engine commercial fleet operations in single-cylinder test stands.

As diesel engines are modified to achieve low exhaust emissions, new and improved fuels and lubricants evaluation methods are necessary. Changes such as higher fuel injection pressures, electronic engine controls, and higher top ring placement on the piston will help achieve lower emissions. Requirements for low oil consumption and for lubricants that are compatible with oxidation catalysts and capable of maintaining long engine life will result in new or revised additive-treated lubricants.

Changes in diesel fuel mandated by the U.S. Environmental Protection Agency and the California Air Resources Board may require changes in lubricants and additives to improve combustion and to control injector deposits. Opportunities abound for advanced product technology. SwRI offers extensive capabilities in diesel engine lubricants research, including:

• Crankcase oil soot loading
• Diesel fuel additives
• Combustion improvers
• Injector deposit control
• Component wear and life
• New procedures and development of lubricants for alcohol- and natural gas-fueled heavy-duty engines
• Lubricant-emissions relationship studies
• New and revised multi-cylinder and single-cylinder procedures
  • Detroit Diesel
  • Mack
  • Cummins
  • John Deere
  • General Motors
  • Caterpillar 
• Lubricants for advanced technology engines
• Low-friction engine lubricants

In addition to standardized testing, the Institute offers screening tests and other specialized or focused laboratory test procedures.

Gasoline Engine Lubricants

The 288-hour VE engine oil performance test simulates stop-and-go urban and moderate freeway driving.

The Institute offers complete testing services for a variety of four-stroke cycle lubricant specifications, including SAE, ASTM, ILSAC GF-3, GF-4 and GF-5 as well as API service classification SL, SM and SN engine oils.

Standardized testing includes:

• The Ball Rust Test evaluates the anti-rust ability of fluid lubricants.  The procedure is particularly suitable for the evaluation of automotive engine oils under low-temperature, acidic service conditions.
  
  

• The Sequence IIIF procedure measures oil thickening and piston deposits under high-temperature conditions and provides information about valve train wear. The test simulates high-speed service under relatively high ambient conditions. A 1996/1997 231 CID (3,800 cc) Series II General Motors V-6 fuel-injected gasoline engine is used.  Using unleaded gasoline, the engine runs a 10-minute initial oil-leveling procedure followed by a 15-minute slow ramp up to speed and load conditions. It then operates at 100 bhp, 3,600 rpm, and 155 degrees C oil temperature for 80 hours, interrupted at 10-hour intervals for oil level checks.
  
  

• The Sequence IIIG test evaluates engine oils for its ability to protect against oil thickening and engine wear during moderately high-speed, high-temperature service.  A 1996/1997 231 C.I.D. (3800 CC) Series II General Motors V-6 fuel-injected gasoline engine is used for this procedure.
  
   

• The Sequence IVA test evaluates an automotive lubricant’s ability to protect against cam lobe wear for overhead valve train equipped engines with sliding cam followers.  The test is conducted on a Nissan KA24E engine with 24L displacement, water-cooled, fuel-injected, four-cylinder in-line overhead camshaft.  Camshaft lobe wear is measured at seven locations around 12 lobes.  Secondary results include cam lobe nose wear and measurement of iron wear metal concentration in the used engine oil.
  
   
• The Sequence VG test evaluates an engine oil’s control of deposits under operating conditions selected to accelerate deposit formation.  The test engine is a Ford 4.6L, spark ignition, four-stroke, eight-cylinder V configuration.  Features of this engine include an overhead camshaft, a cross-flow fast-burn cylinder head design, two valves per cylinder and electronic port fuel injection.  It is based on the Ford 4.6L EFI Crown Victoria passenger can engine.
  
   

• The Sequence VIB (ASTM D 6837) procedure measures the effects of automotive engine oils on the fuel economy of passenger cars and light-duty (3,856 kg, 8,500 lb or less gross vehicle weight) trucks equipped with a low-friction engine.  The Sequence VIB test uses a 1993 4.6-liter Ford modular V-8 gasoline engine equipped with an external oil heating/cooling system and a flying flush system for changing oil without an engine shutdown.
  
   

• The Sequence VID test measures the effects of automotive engine oils on the fuel economy of passenger cars and light-duty trucks.  A 2008 3.6L V6 General Motors gasoline engine equipped with an external oil heating/cooling system and a “flying flush” system for changing oils without an engine shutdown is used for this test.  Test results are expressed as a percent change in kg of fuel consumed for the candidate oil after aging phase I and after aging phase II relative to the baseline oil before and after candidate oil.
  
   

• The Sequence VIII test evaluates automotive engine oils for protection of engines against bearing weight loss.  This method covers SAE grades 5W, 10W, 20, 30, 40 and 50, as well as multi-viscosity grades, used in spark-ignition engines.  An oil is evaluated for its ability to protect the engine and oil from deterioration under high-temp and severe service conditions.  Correlation of test results with those obtained in automotive service has not been established.  This procedure uses a carbureted, spark-ignition Cooperative Lubricant Research Oil test engine run on unleaded fuel.  The test length is 40 hours and test speed is 3150 r/min.  Test oil temperature is 143 degrees C or 290 degrees F.  At the end of the test, the connecting rod bearing weight loss is measured.

   

SwRI evaluates bearing weight loss using L-38 standard lubricant test stands.

Gasoline Two-Stroke Cycle Lubricants

Concern over energy conservation and environmental pollution has led to leaner oil-to-fuel ratios, which, in turn, have affected lubricant requirements. Exhaust emission reduction could contribute to the two-stroke cycle engine's viability in the near future. The two-stroke cycle engine provides better power-to-weight ratio, higher specific power output, and less frictional loss than the four-stroke engine. Many major automobile manufacturers have already built experimental fuel-injected, two-stroke cycle engines for automotive applications.

The Institute evaluates lubricants used in two-stroke cycle, air-cooled engines using the ASTM-TC test sequence, which evaluates the lubricant's ability to:

• Resist combustion chamber deposit-induced preignition
• Prevent ring sticking
• Inhibit deposit formation
• Reduce scuffing
• Resist spark plug fouling

SwRI also offers all engine and chemical tests required to evaluate lubricants for two-stroke, water-cooled engines, including the National Marine Manufacturers Association TC-W3TM specification tests. These requirements have led to improved lubricants that exhibit higher levels of resistance to ring sticking and loss of cylinder compression. In the future, biodegradability of lubricants may become a significant factor for lubricants formulated for the boating industry.

For two-stroke, air-cooled engines, the International Standards Organization (ISO) has recently adopted worldwide test procedures to evaluate lubricants for exhaust smoke, exhaust system deposits, lubricity, and piston cleanliness. These test methods, conducted by SwRI, have supplemented the ASTM-TC specification tests previously used by industry.

With trained personnel and modern laboratory facilities, SwRI helps the petroleum industry monitor future trends and develop lubricants that meet current requirements. In addition, SwRI engineering and technical staff members are available to develop and operate special two-stroke cycle laboratory tests or to design and coordinate custom field tests to meet unique requirements.

Advanced Technology

Advanced spark-ignited, two- and four-stroke cycle engines operating on gasoline, alcohol, natural gas, or mixed fuels sometimes require improved or specialized lubricants. Test services are usually customized and frequently incorporate modification of existing test methods.

Following testing, specially trained gasoline and diesel engine lubricants personnel visually rate parts for sludge, rust, varnish, carbon, and wear. SwRI staff members lead industry workshops and help develop new rating aids and techniques.

Institute staff members have expertise in many areas, including:

• European CEC test methods
• Modified Sequence VI: evaluation of fuel/additive effects on fuel economy
• Fuel-efficient engine oil performance in reduced-friction engines
• Alcohol fuels/alternative fuels
  • Engine durability
  • Ring and bore wear
  • Lubricant evaluation
  • Fuel additives 
• Engine/component durability testing
• SAE J1312 engine power mapping
• SAE J1349 engine power test
• Modified sequence tests
• Piston aircraft lubricant tests
• Exhaust valve seat recession
• Induction system deposits
• Port fuel injector deposits/injector flow loss
• Oil-foaming tendency and aeration
• Low-temperature evaluation
• Turbocharger durability and lubrication
• Real-time kinematic viscosity

The Institute's experienced staff members provide special assistance in experimental projects to develop customized test procedures and precise test equipment for measurement and control.

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