putty for new drain vavle

[slocy]

After much work and going through the closest floor I have managed to pull out the white plastic drain valve from my 23 ft, 2015 INTERNATIONAL. The old one looks like it has some blue putty-like substance around the threads that go into the piece of hose. Any suggestions what this blue putty-like is, should I use the same for new plastic plug or just put some plumber's putty around opening?