Thank you for your question. I assume this is providing the information I requested from your prior question. The two species of trees you are proposing to graft are not compatible genetically. Oak trees (quercus) are in the Fagaceae family. Crabapples (malus) are in the Rosaceae family. Grafting unions fail since these plants are too different at the DNA level. Here is an article that explains it: https://homeguides.sfgate.com/can-graft-different-types-fruit-trees-together-60466.html Hope this is helpful. Good luck!
Thank you so much for the answer, so what would you recommend to graft apple tree to?
You can graft any other member of the Malus genus (https://en.m.wikipedia.org/wiki/Malus) and you can try plants from the larger Rosaceae family (https://en.m.wikipedia.org/wiki/Rosaceae). The closer you stay to the genetics of your crabapple (malus), the better the chances of a successful graft. It’s rather like encouraging humans to mate with other humans (Homo sapiens) rather than with gorillas and monkeys (primates all!) Good luck!