I always use a chocolate with a minimum of 56-60% cocoa solids. A ganache made with equal proportions of this chocolate plus manufacturing cream comes out with the perfect glazing consistency. I recently tried a chocolate with 70%(i think) cocoa solids. I did my usual ganache recipe and it is way too viscous, I had to increase my proportion of cream and it turned out great. Also in its melted state it is too thick for dipping. My question is: when using a chocolate with a higher cocoa solids %, does one need to add a bit more cocoa butter to thin it out? Can you use oil? And is it more viscous because it has less sugar or less fat?