Beautiful hair OP!
When I was WL I used to straighten my curly hair with Kemi Oyl until I found out that oil and flat irons are the equivalent of deep frying your hair/ends. Silcones, like Redken Smooth Down or Sabino Moisture Block, are better because the silcone acts as a "buffer" to protect the hair; it absorbs most of the energy from the heat so the hair doesnt incur damage.
Just FYI, because I was 100% natural pre BkT and all 3b/c with very, very strong hair and I got shredded, split ends and didnt know why. I started using silicones and even Tresseme heat protectant and havent had any problems and I flatiron once a week in the Summer (to avoid sitting under my flaming hot dryer).
Sent from my SGH-T959V using SGH-T959V