I am sure this question has been asked many times, I am going to use the "newbie" excuse for asking it. As I was doing some cleaning in "Miss Doris" today I found several old oil change stickers on the doors jam, one was clear showing they used 10w-40 oil. I use 15w-40 Rottella in my Ram, is this weight too heavy for this Benz or the 10W-40 that was used previously by the mech who service this car?