ASTM D 6681:2023

1.1 This test method covers and is required to evaluate the performance of engine oils intended to satisfy certain American Petroleum Institute (API) C service categories (included in Specification D4485 ). It is performed in a laboratory using a standardized high-speed, single-cylinder diesel engine. 4 Piston and ring groove deposit-forming tendency and oil consumption is measured. The piston, the rings, and the liner are also examined for distress and the rings for mobility. 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 Exceptions- Where there is no direct SI equivalent such as screw threads, National Pipe Threads/diameters, tubing size, or where there is a sole source supply equipment specification. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Being an engine test method, this standard does have definite hazards that require safe practices (see Appendix X2 on Safety). 1.4 The following is the Table of Contents: Section Scope 1 Referenced Documents 2 Terminology 3 Summary of Test Method 4 Significance and Use 5 Apparatus and Installation 6 Intake Air System 6.2.1 Exhaust System 6.2.2 Fuel System 6.2.3 Oil Consumption System 6.2.4 Engine Oil System 6.2.5 Oil Heating System 6.2.5.1 Oil Sample Valve 6.2.5.2 Engine Coolant System 6.2.6 Engine Instrumentation 6.2.7 Reagents and Materials 7 Oil Samples 8 Preparation of Apparatus 9 General Engine Assembly Practices 9.1 Complete Engine Inspection 9.2 Copper Components 9.3 Engine Lubricant System Flush 9.4 Engine Piston Cooling Jets 9.5 Engine Measurements and Inspections 9.6 Cylinder Head 9.7 Valve Guide Bushings 9.8 Fuel Injector 9.9 Piston and Rings 9.10 Cylinder Liner 9.11 Compression Ratio 9.12 Engine Timing 9.13 Engine Coolant System Cleaning Procedure 9.14 Calibration and Standardization 10 Test Cell Instrumentation 10.1 Instrumentation Standards 10.2 Coolant Flow 10.3 Re-calibration Requirements 10.4 Fuel Injectors 10.5 Air Flow 10.6 Intake Air Barrel 10.7 Fuel Filter 10.8 Oil Scale Flow Rates 10.9 Calibration of Test Stands 10.10 Extending Test Stand Calibration Period 10.11 ...

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