According to VW/Audi, "long life oil" (VW 503 00/VW 503 01) must be used only in approved motors. VW/Audi claim the high temperature viscosity of these "long life oils" is considerably lower than that of other oil (VW 500 00/VW 502 00). They also claim that these oils will fail to lubricate properly at high oil temperatures and high RPM in motors that are not approved for those "long life oils." My questions: 1. Which oils are actually "long life oils" in the US? 2. Does anyone know what the difference between VW 500 00 and VW 502 00 is? 3. I'm using M1 0W-40, which fulfills VW 502.00 (See question # 2) and VW 503.01 (long life oil). Since this oil is rated as both, a "long life oil," but also as a "regular" (for lack of a better term) oil, there is no danger for my motor, which was not made for "long life oil," right?