Originally Posted By: KrisZ
If a certain performance level is required form the oil, the manufacturer will create a specification that the oil has to meet. Why would a manufacturer use such a vague specification as "synthetic"? That word has no technical meaning what so ever.
Valid point there. Though, "synthetic" does mean Class III or Class IV, technically. Like in dexos1, GM never said it had to be synthetic, though the performance requirements mean nobody can make a Group II conventional oil good enough, it has to at least be a synth blend.