ASTM D4858 Method for Determination of the Tendency of Lubricants
ASTM D4858 Standard Test Method for Determination of the Tendency of Lubricants to Promote Preignition in Two-Stroke-Cycle Gasoline Engines
1. Scope
1.1 This test method evaluates the performance of lubricants intended for use in two-stroke-cycle spark-ignition gasoline engines which are prone to preignition.
1.2 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.
1.3 The values stated in SI units are the standard. The values given in parentheses are provided for information only.
2. Referenced Documents
2.1 ASTM Standards:
B 152 Specification for Copper Sheet, Strip, Plate, and Rolled Bar
D439 Specification for Automotive Gasoline
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and the Calculation of Dynamic Viscosity)
D664 Test Method for Acid Number of Petroleum Products by Potentiometric Titration
D874 Test Method for Sulfated Ash from Lubricating Oils and Additives
D910 Specification for Aviation Gasolines
D2270 Practice for Calculating Viscosity Index from Kinematic Viscosity at 40° and 100°C
D2699 Test Method for Research Octane Number of Spark-Ignition Engine Fuel
D2700 Test Method for Motor Octane Number of Spark-Ignition Engine Fuel
D2885 Test Method for Research and Motor Method Octane Ratings Using On-Line Analyzers
D2896 Test Method for Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration
D4857 Test Method for Determination of the Ability of Lubricants to Minimize Ring Sticking and Piston Deposits in Two-Stroke-Cycle Gasoline Engines Other than Outboards
D4863 Test Method for Determination of Lubricity of Two-Stroke-Cycle Gasoline Engine Lubricants
E 230 Specification and Temperature-Electromotive Force (EMF) Tables for Standardized Thermocouples
2.2 ANSI Standard:
ANSI MC 96.1 American National Standard for Temperature Measurement Thermocouples
3. Terminology
3.1 Definitions:
3.1.1 combustion chamber - in reciprocating internal combustion engines, the volume bounded by the piston crown and any portion of the cylinder walls extending above the piston crown when in the top dead center position, and the inner surface of the cylinder head including any spark plugs and other inserted components.
3.1.2 preignition - in a spark-ignition engine, ignition of the mixture of fuel and air in the combustion chamber before the passage of the spark.
3.1.3 scuff, scuffing - in lubrication, damage caused by instantaneous localized welding between surfaces in relative motion that does not result in immobilization of the parts.
3.1.4 spark plug fouling - deposition of essentially nonconducting material onto the electrodes of a spark plug that may, but will not necessarily, prevent the plug from operating.
3.1.5 spark plug whiskering, also spark plug bridging - a deposit of conductive material on the spark plug electrodes which tends to form a bridge between them, thus shorting out the plug.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 major preignition - preignition that causes a temperature increase of 10°C (18°F) or more measured at the inner surface of the cylinder head.
3.2.2 minor preignition - preignition that causes a temperature increase of more than 7°C (13°F) and less than 10°C (18°F) measured at the inner surface of the cylinder head.
