Originally Posted By: Garak
He was pointing out that going out of grade or spec isn't going to cause an MB engine to blow up. Going out of spec can be done if one is cautious, reasons things thoroughly, and one's driving habits justify it. If a newish Benz is used as a grocery getter or by grandma going to bingo and the oil is changed sufficiently frequently, even a GF-5 type conventional won't be the end of the world. I wouldn't recommend it, but it's far from the end of the world.
The specs are there for a reason, but we needn't act as if we're trying to run a 110 V appliance off of double the voltage. MB did include 5w-20 and all kinds of other light grades, weather permitting, not all that long ago. How thin is any oil going to get, even something a grade thinner than recommended, after a five block trip?
That being said, 10w-30 is an odd choice, even if it were an approved lube. If it were on the approval list, it would likely be one of my last choices.
So wait, he bought SLK55 AMG to drive it nice? There is Camry for that!