Did the navajos use oral or written more?

Navajo traditional culture had and has a preference for oral transmission. As with most North American native cultures, they did not have a written language. Now they do, but still the preference for many people is oral for traditional knowledge and stories and ceremonies.

The "medicine men" the traditional Navajo ceremonial ritual leaders known in Navajo as Hataałii, must learn the ceremony and all the prayers and song exactly by heart without taking notes. It takes many years. Traditional stories are not supposed to be told in times when it is not winter so some feel they should not be written down.

There also is a deeper cultural preference for things to be in a dynamic symmetry of balanced forces rather than static. Writing them down prevents that dynamic balance between remembering something as exactly as you can and the gradual change that is necessary for things to live.

There also was a preference against permanent pictorial representation. Sand painting were swept up after the ceremony. People did not paint images on pottery or put it in rugs. There were many people who were upset when some other people started putting images in rugs and painting sandpainting designs for permanent display. Hoteen Klah (Navajo: Hastiin Tłʼa) was one of the earliest to do this. He was a medicine man (18167-1937) who felt important knowledge would be lost. Others thought it would make people sick or die.