The sun although without it we would all die can cause damage for your hair and skin if exposed to too much, it can also change the color of your hair turning it the completely wrong shade so you need to make sure your products have UV protection as well as cover up when possible.
Now if your white you want to have some color so you may need to wear a hat the times your out, even if it’s for a short time the excessive heat causes the internal moisture of your hair to evaporate and dry up. If your still hung up using oil as a “natural” remedy for dry hair then keep reading!
Even though you wash out your oil ( which does nothing btw ) small molecules are left behind and over time build up. Oil + Sun heats up the hair drying it out faster and burning the oil onto your hair making it shinny yes, but burnt, damaged, rough and dry! Don’t do it!!!