Heat protectant spray is not optional, learned that the pricey way

I used to skip heat protectant because my hair felt fine afterward and the spray made my roots look greasy. Then last summer I got really into using a flat iron almost every day for about 4 months. By September my ends looked like straw and I had to chop off 5 inches at a salon in Portland. My stylist asked if I ever used any protectant and I admitted I basically never did. She showed me the split ends under her microscope thing and it was so obvious. Now I spray a light mist on damp hair and let it dry before styling. It doesnt weigh my hair down at all if I use a tiny amount. Has anyone else found a heat protectant that works for fine hair without making it oily?