Hey Chris, I used to use Coconut oil as a a "heavy oil" but I didn´t really like the smell. I now use a more odourless oil like argan or olive. I always add a few drops of fragrance oil to the final mix - I like fresh notes like orange and pepper.

I have written a bit about different beard products here:
moustache cups and mugsbeard brushes and combs
beard literature | simple homemade beard oil

my beard journey | my bart * aber herzlich beard oil | Bartöl store (external link, not affiliated with or endorsed by beard board)