I havent tried MaxLife but I have used Chevron supreme oil (sold in cases of 12 at Costco) 20w50 in my 300e with excellant results. I also added a bottle of Mobil 1 TriSynthetic 10w30. I use the Mobil 1 205 filter. I used to consume a bottle of oil a week (400 miles) but now with this combo I have only used 2 bottles in 3000 miles.
Many others have mixed in 1 bottle of Mobil1 and got similar results. Also, Castrol 20W50 is what Mercedes were initially were putting in the 300E even in cold climates. If you are not really burning oil and really love your 300E, go buy a case of Mobil1. I doubt you will have leaks.