I used the black OEM stuff from the dealer and it has held up fine for several months now - I think proper preparation i.e. cleaning of the mating surfaces is the most critical step. If the mating surfaces are 110 percent oil-free and you torque properly, you could probably use bubble gum and it would hold.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280