Should I use olive oil on my hair or buy hot oil for a weekly treatment?

Have you tried all the various ways of making your hair stronger, shinier and healthier. What is the best way? Also, what would be the best kind of food to eat?Should I use olive oil on my hair or buy hot oil for a weekly treatment?
I had really dry hair after dying it and straighting it, my hairdresser told me to put mayo in my hair for 15 minutes and wash it out. As weird as it was it actually worked very well and was way cheaper then a hot oil treatment.