my corks started to leak and turned into an oily, smokey mess on the highway, i was going to replace them with the fel pro rubber ones, but couldnt seem to get them to stay in place long enough to put the cover on. So i switched back to the cork ones once again. I did use sealant on both sides. But i used aircraft sealant. Its a lot stickier and has not proven me wrong on any application. This was almost a year ago, and i put around 100 miles a day on my 92 ranger. Some may call me an idot, but, it works, and until it doesnt, i wont talk bad about it. Hope this helps.