Topsider at West Marine
 

<<Hi Roger, I went to westmarine.com and found this. Is it also the one you mentioned?>>

Yes, that's the one. I see the price has risen slightly.

Record keeping
 

<<Does doing the oil change yourself create the possibility of voiding the remainder of the factory or CPO warranty on the car, since there would be no evidence of a service paper from a Mercedes dealer or an Independent shop?>>

This question has been asked before and there is no possibility of that. Simply keep a written record of your oil changes which is acceptable to MB.