Testing Motorcycle Engine Oils | JASO T903:2023 Standards

What is JASO T903:2023?

The JASO T903:2023 is a test specification from the Japanese Automotive Standards Organization (JASO) for evaluating motorcycle engine oil performance, with a specific focus on wet clutch compatibility. This updated standard builds upon the JASO T903:2016 specification by introducing a new low-friction reference fluid and an updated friction plate design.

This critical standard classifies four-stroke motorcycle engine oils based on their performance in three key areas:

• Dynamic Friction (DF): Measures the friction properties as the clutch is engaging.
• Static Friction (SF): Assesses the oil's holding power when the clutch is fully engaged.
• Stop Time (ST): Determines how quickly the clutch engages after activation.

JASO T903 Testing Overview

The T903 test is conducted on a standard SAE #2 test machine, a proven system that has been widely used for automatic transmission fluid (ATF) development over decades. The testing process involves 1,000 operating cycles, with data collected from the 400th, 500th, and 600th cycles to calculate the averages for the candidate oil.

These averages are used to calculate three performance indexes:

• Dynamic Friction Index (DFI)
• Static Friction Index (SFI)
• Stop Time Index (STI)

These indexes are derived using performance data from two reference fluids, JAFRE-A16 and JAFRE-B23, and are used to assign one of four classifications to the oil:

1. MA: For motorcycles with wet clutch systems.
• MA2: Subset with higher performance levels.
• MA1: Subset with standard performance levels.
2. MB: For motorcycles with automatic transmissions, such as scooters.

Why Choose Intertek for JASO T903 Testing?

At Intertek, we run the JASO T903:2023 test daily, ensuring rapid, reliable results for our clients. For those still requiring the older JASO T903:2016 specification, we continue to offer this service as well. With extensive experience and state-of-the-art facilities, we help ensure your motorcycle engine oil meets the precise demands of modern engines and wet clutch systems.

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