Overheard this conversation in a waiting room the other day. Lets use Mobil 1 for an example and lets say it is 20 degrees fahrenheit outside. Would the 5W20 and 5w30 flow the same at start up? I guess the same could be asked of the Mobil 1 AFE line. Does the AFE 0W20 and 0W30 flow the same as well?