Originally Posted By: crazyoildude
I never changed the rear axle fluid in this 2004 Mercury Grand Marquis what weight should i use..I am going with Motorcraft from the dealer..Any special additive needed?
Chances are, it's not a posi, very few MGMs had them. They generally have electronic traction control (the '03 in my sig has it, "Precisiontrac"). If so, you won't need any posi additive.