Right now have maybe a cup of veg oil and 1/2 cup canola. Anything else I can use to substitute???
Safflower oil would work. Just wouldn't use olive oil
You can use melted butter for the remainder, but be sure that when you melt it, you let the water cook off. Butter is an emulsion of 80% fat, 18% water, and 2% milk solids. To get the 4 ounces you are lacking, melt 5 ounces of butter and let the water "sputter" away. Excess water in any batter gives gluten a chance to overdevelop and produce a tougher cake.
Use some olive oil but overdose on the sugar
You could also try some other relatively neutral oil, like grapeseed oil if you have it. Peanut might work but I'm not sure how strong 1/2 cup would be in the grand scheme of things. Plus peanut and chocolate kind of go together anyway!