I see recipes that call for canola or safflower oil. I own neither, but do have vegetable oil. Can I sub that and how will it effect the product, ie. cake?
Vegetable oil is a blend of neutral oils, usually including safflower and canola (and often corn and soy). You should be fine using vegetable oil if a recipe calls for canola.
Canola oil and vegetable oil are essentially the same thing. The word "Canola" is a brand name meaning Canadian Oil-Low Acid. It's intended use was as a lubricant, but has been deemed safe for human consumption. FYI! Adding a little to your more flavorful fats, like butter or olive oil, will raise their smoking point!