ASTM-D8047 Historical Revision Information
Standard Test Method for Evaluation of Engine Oil Aeration Resistance in a Caterpillar C13 Direct-Injected Turbocharged Automotive Diesel Engine

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Standard Test Method for Evaluation of Engine Oil Aeration Resistance in a Caterpillar C13 Direct-Injected Turbocharged Automotive Diesel Engine


1.1 This test method evaluates an engine oil's resistance to aeration in automotive diesel engine service. It is commonly referred to as the Caterpillar-C13 Engine-Oil Aeration Test (COAT). The test is conducted under high-engine-speed (1800 r/min), zero-load conditions using a specified Caterpillar 320 kW, direct-injection, turbocharged, after-cooled, six-cylinder diesel engine designed for heavy-duty, on-highway truck use. This test method was developed as a replacement for Test Method D6894.

Note 1: Companion test methods used to evaluate engine oil performance for specification requirements are discussed in the latest revision of Specification D4485.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.2.1 Exception—Where there is no direct SI equivalent, for example, screw threads, national pipe threads/diameters, and tubing size.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See Annex A2 for general safety precautions.

1.4 This test method is arranged as follows:





Referenced Documents




Summary of Test Method


Significance and Use




Engine Liquids and Cleaning Solvent


Preparation of Apparatus


Engine Stand Calibration and Non-Reference-Oil Tests




Calculation, Test Validity and Test Results




Precision and Bias




ASTM Test Monitoring Center Organization

Annex A1

Safety Precautions

Annex A2

Engine and Engine Build Parts Kit

Annex A3

Oil Temperature Control System

Annex A4

Engine Modifications and Instrumentation

Annex A5

External Oil System

Annex A6

Aeration Measurement System

Annex A7

Specified Units and Formats

Annex A8

ASTM TMC: Calibration Procedures

Annex A9

ASTM TMC: Maintenance Activities

Annex A10

ASTM TMC: Related Information

Annex A11

Engine Break-in and Silicon Passivation Procedure

Annex A12

Schedule for Taking Oil Samples and Carrying out Analyses

Annex A13

Determination of Operational Validity

Annex A14

Specification for PC-10 ULSD Fuel

Annex A15

Typical System Configuration

Appendix X1

Significance and Use

5.1 Background—Prior to this test method, the ability of an engine lubricant to resist aeration was measured by the engine-oil aeration test (EOAT) described in Test Method D6894. The continued availability of engine parts coupled with field service aeration problems led to concerns about the relevance of this test method to newer oil and engine technologies. These concerns prompted the development of this new engine-oil aeration test method, based on the Caterpillar C13 engine and termed COAT. This test method aims to provide a more reliable measurement of the ability of a lubricant to resist aeration during engine operation in field service. The engine used is of current technology and the aeration measurement is operator independent.

5.2 Test Method—This test method evaluates aeration performance under high-engine-speed, zero-load operation in a turbocharged, heavy-duty, four-stroke diesel engine.

5.3 Use: 

5.3.1 The tendency of engine oils to aerate in direct-injection, turbocharged diesel engines is influenced by a variety of factors, including engine oil formulation, oil temperature, sump design and capacity, residence time of the oil in the sump, and the design of the pressurized oil systems. In some engine-oil-activated systems, the residence time of the oil in the sump is insufficient to allow dissipation of aeration from the oil. As a consequence, aerated oil can be circulated to hydraulically activated components, adversely affecting the engine timing characteristics and engine operation.

5.3.2 The results from this test method may be compared against specification requirements such as Specification D4485 to ascertain acceptance.

5.3.3 The design of the test engine used in this test method is representative of many, but not all, diesel engines. This factor, along with the unique operating conditions, needs to be considered when comparing the test results against specification requirements.


automotive; Caterpillar C13; COAT; diesel engine oil; heavy-duty diesel engine; lubricants; oil aeration;; ICS Number Code 75.100 (Lubricants, industrial oils and related products)

To find similar documents by ASTM Volume:

05.04 (Petroleum Products and Lubricants (IV): D6973 - latest)

05.05 (Combustion Characteristics; Manufactured Carbon and Graphite Products; Catalysts)

To find similar documents by classification:

75.100 (Lubricants, industrial oils and related products Including mineral oils, fluids for metal working and for temporary protection against corrosion Lubrication systems, see 21.260 Insulating oils, see 29.035.40)

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Document Number


Revision Level




Modification Type


Publication Date

July 1, 2016

Document Type

Test Method

Page Count

42 pages

Committee Number