Hot take: I stopped greasing my neck dam after a job in Galveston and it fixed my suit leaks
Was doing a 3 week pile job in Galveston Bay about 4 years back and kept getting water seeping down the back of my neck on every dive past 40 feet. The guy I was partnered with, 20 years in the Gulf, told me to quit slathering grease on the dam because it was actually making the seal worse by letting it slide around. Switched to just wiping it down with a dry rag and checking the fold before every splash, and the leaks quit. Anyone else run into this or am I just lucky it worked?
That bit about letting it slide around is dead on. Buddy of mine dove the Gulf for years and had the same thing happen on a job out of Morgan City, kept fighting a wet neck every dive until an old timer told him the grease was just giving the seal room to shift. He started wiping the dam dry with a shop towel, making sure the fold sat flat before he zipped up, and the seepage stopped pretty much right away. Cheap fix, too.