Can I use Tea Tree Oil on Keratin treated hair?

I have been using tea tree oil in my shampoo for over 2 years. I mix 20 drops with 16oz of my shampoo and 20 drop with 16oz of my conditioner. I recently got my hair keratin treated and i have keratin shampoo and conitioner. Can I use tea tree oil in the keratin shampoo and conitioner?