API Oil Service Categories

Hannu Jääskeläinen

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Abstract: API oil service categories are used to differentiate and to provide testing requirements for North American heavy-duty diesel engine lubricants for different applications.

Introduction

API oil service categories are widely used to differentiate North American heavy-duty diesel engine lubricants for different applications. Some of the more recent service category requirements are summarized below. Additional details on specific test limits for compression ignition and spark ignition engine oils can be found in ASTM D4485 and SAE J301. SAE J301 also provides details about obsolete API service categories.

API CF Category

This API category introduced in 1994 is intended for off-road diesel engines using a range of diesel fuels including those with more than 0.5% sulfur. Oils needed to pass two engine tests to meet the requirements of this classification:

  1. Caterpillar 1M-PC test, ASTM D6618. This test method uses a four-stroke single cylinder indirect injection diesel engine. It has been shown to correlate with oil performance in naturally aspirated, turbocharged and supercharged indirect injection diesel engines. For this service category, this test is used to evaluate engine oils for high-temperature performance characteristics related to:
  2. CRC L-38 Spark-Ignition Engine, ASTM D5119. The test procedure uses a carbureted, spark-ignition Cooperative Lubrication Research (CLR) L-38 Oil Test Engine. The engine operates under high-temperature, heavy-duty service conditions. For this service category, this test is used to evaluate the weight loss of copper-lead bearings used in the test power section.

API CF-2 Category

This API category introduced in 1994 is intended for two stroke diesel engines. A lack of replacement parts and service stands to run some of the engine tests for this category means that it is destined for obsolescence.

Oils needed to pass three engine tests to meet the requirements of this classification:

  1. Caterpillar 1M-PC test, ASTM D6618. While this test method uses a four-stroke single cylinder indirect injection diesel engine, it able to relate piston and ring groove deposit control for two-stroke diesel engines when used with a modified piston deposit rating methodology.
  2. CRC L-38 spark ignition engine test, ASTM D5119, as used in the CF category.
  3. Detroit Diesel 6V-92TA test, ASTM D5862. This test method uses a two-stroke cycle diesel engine for evaluating engine oils for certain high-temperature performance characteristics. For this API category, this test is used to evaluate:

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