When you transplant an oak tree, you run the risk of killing the tree. A good rule of thumb is that the smaller the tree, the easier it is to transplant. You should not try to move an oak tree older than 60 years old. The trees have extensive, deep root systems. You must determine if an oak tree is healthy enough to move before doing anything else. If the diameter of the trunk and the tree's canopy are small, and if the tree is growing in an open field, it's a good candidate for transplanting.
Use a hose to water the soil and tree foliage heavily. Both should be saturated before you attempt transplantation.
Assume there is just as much tree underground as you see above ground. If the oak has a 10-foot-wide canopy that is 5 feet high, then the roots are 10 feet wide and 5 feet deep.
Dig around the root ball with a shovel. Make the area you shovel out wide enough to ensure that you don't damage too many roots. Get the shovel in the soil as deep as you can. If you run into a difficult root, cut it with pruning shears.
Get help and slowly lift the oak tree from its hole. It will be heavy. Water the roots again to keep them saturated.
Dig a hole in the new location, making it as deep and wide as the one you've left behind. Pour water into the hole and place the root ball of the oak in the middle. Cover with soil and water thoroughly. Transplanted trees need more water to help them deal with the stress of moving.
Use stakes to support the oak tree until the roots take hold. This will prevent the tree from leaning or being blown over by the wind.