The older breakfree had particles that would settle to the bottom of the bottle. Had to shake it every time. The older formula was also a little darker and thicker than what I find now, but not like you describe.

If it smells like breakfree (unmistakeable), I would just pick up a can of the spray breakfree at walmart and mix the old stuff 50/50. That spray can breakfree is water thin.

It may not be worth the hassle, though.