Good story!
I have been in the same boat to!
Now I move my moms car into the street before the hood opens up.
Mobil 1 15w-50 is fine, I use it in the summer. The main difference is Mobil 1 Delvac can hold 4% of soot and regular can only do 2%. But MB says don't go over 2%.
Now as to the lifters mine are kind of loud or at least they were. I'll wait to I have used Mobil 1 for 10k before I decide if I want to replace them. As I am driving down the street if I drive next to a large building or anything that reflects the sound I can hear a nice tick.