API API Two-Cycle Motor Oil Specifications

Spec Status Description
TA Obsolete Proposed classification for two-stroke engine oils required for extremely-small engines, typically less than 50 cc. Engine Tests for this classification were under preparation when the Coordinating European Council (CEC) withdrew support for this category.
TB Obsolete Proposed classification for two-stroke engine oils required for the engines of motor-scooters and other highly-loaded small engines, typically between 50 and 200 cc. The test sponsor no longer requires this category, and the classification has been abandoned.
TC Current Designed for various high-performance engines, typically between 200 and 500 cc, such as those on motorcycles and snowmobiles, and chain saws with high fuel-oil ratios - but not outboards. Two-cycle engine oils designed for API Classification TC address ring-sticking, pre-ignition and cylinder scuffing problems.
TD Obsolete Designed for water-cooled outboard engines, this classification used the identical engine test to that in the National Marine Manufacturers association (NMMA) TC-W category. API TD has been superseded, and is no longer accepted by the NMMA, who now recommend oils meeting the requirements of TC-W3 for water-cooled outboard engines.


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