core plug sealant

[moto x]

What should I use to seal my core plugs with?

 

[ArticNemesis]

They actually make a "core plug sealant" that can be used to do it, but I've seen red RTV work as well.

Core plugs are usually dome shaped and when installed properly, you can flatten out the center of the plug using a socket. It forces the outer diameter of the plug to become slightly larger, sealing itself into the block rather nicely.