Overview
ISO 13738:2011 specifies performance and physical/chemical requirements for two-stroke-cycle gasoline engine oils (two-stroke oils) used in crankcase-scavenged, spark‑ignition engines - for example in motorcycles, snowmobiles and chainsaws. The standard defines classification and minimum performance levels for three oil grades EGB, EGC and EGD (from lower to higher performance) and uses engine test‑based performance indices referenced to a standard reference oil (JATRE‑1 = 100).
Keywords: ISO 13738:2011, two-stroke oils, EGB EGC EGD, lubricant standards, two-stroke-cycle gasoline engine oils
Key topics and requirements
- Scope: Applies to crankcase‑scavenged two‑stroke spark‑ignition gasoline engines used in transportation, leisure and utility applications. Annex A gives supplementary notes on outboard motors.
- Physical/chemical limits
- Kinematic viscosity at 100 °C ≥ 6.5 mm²/s (ISO 3104)
- Sulfated ash ≤ 0.18 % mass (ISO 3987)
- Performance classification
- Performance is assessed using six performance indices derived from engine tests covering lubricity, initial torque, detergency, piston skirt deposits, exhaust smoke, and exhaust system blocking.
- Tests and procedures referenced include JASO M340, M341, M342, M343 and CEC L‑079‑A‑99 where applicable.
- Indices are reported relative to the reference oil (JATRE‑1 = 100); each oil category (EGB/EGC/EGD) has minimum index thresholds. Example minima: lubricity index ≥95 (all categories), initial torque index ≥98, higher minima for exhaust smoke and exhaust system blocking for EGC/EGD versus EGB.
- Classification rules
- A candidate oil must meet or exceed the standard index for each performance parameter to be assigned to that category.
- Where multiple test runs are used, ISO 13738 prescribes a statistically based averaging approach (e.g., means for two tests; discard one for three or more).
Applications
- Use ISO 13738:2011 to:
- Specify product formulation targets for two‑stroke engine oil manufacturers.
- Demonstrate conformance for product labeling and supplier specifications.
- Guide OEMs (motorcycle, powersports, small‑engine manufacturers) in lubricant recommendations to consumers.
- Typical end uses: motorcycles, scooters, snowmobiles, handheld power tools (chainsaws, trimmers) and other crankcase‑scavenged two‑stroke equipment.
Who uses this standard?
- Lubricant formulators and manufacturers
- Engine and vehicle OEMs specifying recommended oils
- Testing laboratories performing JASO/CEC engine tests
- Procurement and quality teams ensuring product compliance
Related standards
- ISO 6743‑15 (classification of engine oils, Family E)
- ISO 6743‑99 (general classification)
- JASO M340–M343 and CEC L‑079‑A‑99 (test methods)
- NMMA TC‑W3 (outboard two‑stroke oil specification; referenced for marine applications)
This standard helps align two‑stroke oil performance claims with harmonized test methods and measurable limits, improving lubricant selection and engine life.