ASTM D4859 Lubricants for Two-Stroke-Cycle Spark-Ignition Gasoline Engines-TC
1. Scope
1.1 This specification covers lubricants intended for use in two-stroke-cycle spark-ignition gasoline engines, typically other than outboard motors, that are particularly prone to ring sticking, but which are also liable to suffer damage arising from deposit induced preignition, piston scuff, spark plug fouling and piston varnish.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
2. Referenced Documents
2.1 ASTM Standards:
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
D2270 Practice for Calculating Viscosity Index from Kinematic Viscosity at 40° and 100°C
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
D4858 Test Method for Determination of the Tendency of Lubricants to Promote Preignition in Two-Stroke-Cycle Gasoline Engines
D4863 Test Method for Determination of Lubricity of Two-Stroke-Cycle Gasoline Engine Lubricants
2.2 Coordinating European Council (CEC) Standard:
CEC L-19-T-77 The Evaluation of the Lubricity of Two-Stroke Engine Oils
3. Terminology
3.1 Definitions:
3.1.1 cold sticking - of piston rings, a condition in which the ring is free in its groove while the engine is running but stuck when the piston is cold, normally indicated by the absence of varnish or other deposits on the outer face of the ring and of signs of blowby on the piston skirt.
3.1.2 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.
3.1.3 hot sticking - of piston rings, a condition in which the ring is stuck in its groove while the engine is running, normally indicated by varnish or other deposits on the outer face of the ring, by signs of blowby on the piston skirt, or both.
3.1.4 lubricity - a qualitative term describing the ability of a lubricant to minimize friction between and damage to surfaces in relative motion under load.
3.1.5 preignition - in a spark-ignition engine, ignition of the mixture of fuel and air in the combustion chamber beforethe passage of the spark.
3.1.6 scuff, scuffing - in lubrication, damage caused by instantaneous localized welding between surfaces in relative motion which does not result in immobilization of the parts.
3.1.7 seizure - in lubrication, welding between surfaces in relative motion that results in immobilization of the parts.
3.1.8 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.
3.1.9 spark plug whiskering, or 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 Definition of Terms Specific to This Standard:
3.2.1 benchmark reference oil - an oil meeting the requirements of a test of this specification and whose performance on that test is equalled or exceeded by that of the candidate oil within the specified tolerances.
3.2.2 major preignition - preignition indicated by an increase in the combustion chamber temperature of 10°C (18°F) or more over a period of less than a minute.
3.2.3 minor preignition - preignition indicated by an increase in the combustion chamber temperature of 7°C (13°F) or more but less than 10°C (18°F) over a period of less than a minute.
