68 350 H.O. With a non-original radiator (I think) replaced by the previous owner in 2015. Has never leaked a drop, until about a month ago when I drove 1 mile to a local gathering and about an hour after parking, it started to drip from the drivers side bottom. At first I thought it was the drain [censored] as I was able to tighten it a half turn-ish But , the leak did not stop. It was a very slow drip. I went in the restaurant and ate and when I came out 90 min later it had stopped leaking and the bottom of the radiator was actually dry. It lost maybe a total of 1/4 cup of coolant at the most.

Since then, it has been leaking off and on in my garage. Sometimes it will go days without a drop and other times it may lose a teaspoon over several days. I’ve driven it several times since then as well as that doesn’t seem to affect it one way or the other.

So... my question to the group is how everyone feels about quality stop leak products such as Bar’s? Or, any other suggested solutions for the issue?

Thanks!