I eventually figured out how to make Vegan Butter! It works really well as a drop-in replacement for butter and other margarines because it has the same water to fat ratio as butter. If you don't know about it already, here's the link:
http://veganbaking.net/other-vegan-treats/735-vegan-butter

Very interesting, thanks for all those infos!

And at least it will keep me away from trying again cinnamon rolls with oil (turned out completely flat, hopefully it tasted good) :blush:

Hi Daniel-san,

Welcome to the forums! The 2/3 oil to 1 cup butter or margarine rule is because butter and to a lesser extent, margarine incorporates small amounts of water and even smaller amounts of air. Oil is 100 percent fat in comparison.

Butter and margarine definitely enhances the flavor complexity of your baked item due to it's butter flavor compounds. This is almost a sort of 'umami' which is the Japanese idea of savory, arguably the 5th flavor sense. When I design a recipe I usually prefer to use oil unless the recipe significantly benefits from the flavors of butter. Recipes containing corn, pumpkin, or other savory/sweet elements tend to work out better with margarine's buttery flavors.

Also, it's impossible to make flaky pie crust and puff pastry with oil. This is because these things rely heavily on solid fat both isolating the gluten in the flour by coating it (instead of being absorbed) and the solid fats creating several altering layers that get crispy during baking and allow for leavening caused by these layers expanding.

Hope this clarifies things a little!

Someday I'd love to make a blend of margarine from coconut oil and cocoa butter and some other stuff and see what I can come up with.