You can buy the expanding washers in any HW or BB store to reseal them. A lot of times the road conditions loosen them or the washer wears out and you need to put a new one in. You want one that is v shaped so when you screw down, it will expand and choke the pipe.
The other option is put a new P trap on it. That vaseline will eventually give way to a drip.
2014 375 BHFS Eagle Premier
2014 Ram 3500 Longhorn DRW CC
6.7 CTD, Aisin, 4.10's