Can you mix Flax seed oil and Coconut oil in a smoothie?

I presume you mean adding a small amount of oil to other items such as fruit into a smoothie. Yes you could for added nutritional value. Flax seed oil and coconut oil are both excellent for health and provide complementary fatty acids so why not. A small amount of lecithin might be a good idea if you have capsules you can squeeze the contents of one or two f these into the smoothie mix. Lecithin will help homogenise the oil and water mix. Adding whey protein or natural live yogurt to the fruit and oil mix would make it a good meal substitute for a non-main meal such as breakfast. I wouldn't add too much oil though.