Castrol Canada Inc.

Technical Service Bulletin #229

January, 1996


The oil industry is dynamic. Specifications and test methodology are constantly being created or revised. For example, within the last two years, the system by which motor oils are approved was totally revamped (API SH) and new oil standards and their associated symbols (ILSAC GF-1) were added to the mix of existing specifications.

Once again, a change has taken place in the industry and Castrol has responded. The API Performance Category CD has become obsolete as of January 1, 1996. Oil marketers can no longer use the CD category designation inside the API donut. In fact, Caterpillar, the sponsor of the test which defines CD performance, no longer provides the hardware necessary to run the test. Caterpillar is now committed to sponsoring the test associated with one of the new diesel performance categories, API CF. CF will be a category for off-road, indirect injected, heavy duty trucks.

API CD has served an important purpose. This performance category has long been recognized as providing additional thermal stability to passenger car motor oils. CD performance in these oils provided greater control of deposits and protections against obsolescence of API CD. The industry has established a more precise test (the Thermo-oxidation Engine Oil Simulations Test or TEOST) pertinent to passenger car and light truck high temperature deposits. This new test is part of current and future passenger car lubricant specifications. Chrysler incorporated this test into its service fill engine oil specification back in 1991. The next generation of ILSAC specifications (GF-2) also include this test.

Castrol now markets passenger car motor oils WITHOUT the API CD designation. These new Castrol formulations have been evaluated in the new industry standard. All Castrol formulations exceed current and future requirements for this measurement of thermal stability.

The deletion of API CD will in no way compromise the maximum protection which consumers receive from GTX. We have and always will provide maximum protection against viscosity and thermal breakdown. Passenger cars and light trucks which call for API SG/CD or SH/CD can confidently continue to use Castrol GTX. This applies to gasoline, diesel and turbocharged engines. For those diesel passenger cars and trucks which call for API CD, API CF-4 or API CG-4, Castrol RX Super 15W-40 is recommended. Castrol RX Super 15W-40 can offer improved deposit control and wear protections for these special diesel applications.

The Engine Oil Bible