API API Two-Cycle Motor Oil Specifications
|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 API TD has been superseded, and is no longer accepted by the NMMA, who now recommend oils meeting the requirements of TC-W3 for water-cooled outboard engines.|