Hello, Out to replace the dexcool in my radiator in my 98 Chevy S-10 ZR2 pickup. I tried to turn the stopcock, and couldnt for the life of me. The thing is set up so you turn it maybe a quarter, then it slides out. I gently used a pliers to turn the thing, but then couldn't pull it out. I had to use a screwdriver to gently pry it out to the point where the coolant would start flowing, and then it was still really hard to get out. I eventually got it out all the way, and am finding the o-ring a bit hard. Should I use some sort of grease to make it easier to use the stopcock, or is it best after 10+ years to just replace? THanks!