Using Bondo for Wood Repair

Is there a special formulation or some kind of additive that I can add that will make bondo more flowable without upsetting the setting action?
Plastik honey by evercoat
Or fiberglass resin bondo brand should ride

Sometimes reducer and sometimes denatured alcohol. The latter seem to shrink a little more

Evercoat also makes a glazing coat product that I mix with thicker mud too… green label