I have a question about formulations. It is my understanding that the dope of today is not compatible with the dope of yesterday (15+ years ago). I was told that the formulation was changed to meet some EPA mandate. I'm told that the new formula will lift the old formula when trying to make a patch repair.
So I'd like to know if this is in fact true and if so does it apply to both Nitrate and Butyrate dopes.

All the best,

Konrad