NMMA TCW-3 tests incorporate a run on a 2-stroke air cooled engine as part of the certification although the majority of the test is on water-cooled engines.

That said, the API-TC, ISO-EGD, and JASO-FC are more stringent tests and are strictly for air cooled engines.

There is a difference between the "testing regimen" and real-world experiences however.

Real world experiences demonstrate the Royal Purple TCW-III certified oil will work well in our engines.