A test was developed to determine the effect of licensed DEXRON®-III service fluids on the performance of the Electronically Controlled Capacity Clutch (EC3). Some fluids can cause shudder and/or hunting of the clutch and are unsuitable for use in EC3-equipped vehicles. The test uses a 1997 Riviera with a 3800 SC engine and a 4T65E transmission to evaluate fluids under a variety of driving conditions. The responses to both the reference and candidate fluids are statistically compared with each other and with pooled data from previous reference tests to identify and reject unsuitable fluids. The DEXRON®-III specification has been modified to include this test to ensure the elimination of unsuitable DEXRON®-III fluids from the marketplace.