While we have had success with just about every kind of extract with enough trial and error, VISCOSITY was designed to be combined with winterized extracts; meaning those which have had the the majority of the lipids (fats) and waxes removed. Generally winterized extracts include distillate and post processed (finished/polished) CO2.
As a rule of thumb, if an extract is not transparent it likely contains a high content of lipids and waxes which will likely separate when a high content of terpenes is added. If your extract separates, it is not ruined. Though you may want to consume it using another method.
DISTILLATE: Best use
CO2: Best use
BHO: If it is transparent shatter VISCOSITY works well. With crumble, wax, pull and snap, or other soft or granular forms of BHO VISCOSITY may cause separation of lipids and waxes
VISCOSITY combines well with BHO if it is in the form of a transparent shatter. Opaque BHO tends to have more lipids and waxes which separate when exposed to excess terpenes.
ROSIN: If it is transparent rosin, VISCOSITY works well. With dark, opaque rosins VISCOSITY may cause separation of lipids and waxes
SOLVENTLESS: Not suggested