The SL-rated M1, can't attest to the others. Got a '07 Impala with the 3.5L and about 120,000mi, switched it from Valvoline Maxlife blend 5w30 to Mobil 1 HM 5w30. The oil I took out had about 6000mi on it. I didn't really expect to notice anything different because the engine runs fine, but I can say this- the M1 seems to lubricate better, especially during a cold start. Any valvetrain sound I considered normal is actually less pronounced, and no more startup starvation which everyonoe hates to hear, no matter how minor. Bosch distance plus filter used before and after. I know a lot of people like Pennzoil here but I do not think you can go wrong with M1 oil. I'm just not sure it is even possible to make an oil as good with the SM or SN rating, maybe I'm wrong but I notice a difference in my car.