Rubber expansion plugs my thoughts (core/freeze plugs)

These rubber expansion plugs were the only way I could stop a leak having tried traditional steel/SS and brass plugs with various sealants as well as dry. My experience has been a good one. I made sure I thoroughly tested for leaks on the driveway (hard revs and getting up to temperature before taking on the road). May be an option of keeping an old car going for a few years if you too are having problems with persistent leaky core plugs. Note there could be underlying reason other than age/wear and tear as to why core/freeze plugs leak, such as a blown head gasket. I thought that may have been the case with this car as I just could not fathom why the metal plug that I replaced kept on leaking. But a year later and engine is fine, so confident wasn't blown head gasket. Good luck!