I've never had a lot of experience with grey fox as they have just recently showed up in my area so i'm not sure if they will require a new type set and lure. If greys are like red fox and coyotes, you'll need to make another trail set or blind set with just plain urine or something entirely different as an attractor. I like to make a perfectly blended set at a clum of grass or natural projection and lure it with plain urine or mink lures as a change-up. Good luck! Ace