Permatex Cap

thingiverse

Permatex caps always crack and then all the sealant hardens inside the tube. This cap will not crack or break (at least mine haven't) and they seal much better than the original cap. I've still experienced a little hardening of the sealant right at the top of the tube but I just clean that out with a wood screw and it's good to go. If you have trouble removing the cap (I haven't) a 15mm wrench fits on the cap.