Generally seeing an oak tree in your dream signifies that the following period of time will be filled with strength and energy. Your health will be very good and you will feel unusually refreshed despite the significant efforts that you will undertake.
Seeing a very old oak tree signifies longevity. The longevity in your case will come as a result of your own healthy habits and as a result of you avoiding doing anything that will put undue strain on your body. If you are sick and you dream of an old oak it signifies that you will overcome your illness soon.
To sit under the shade of an oak tree is indicative of you valuing the efforts that are made by your friends and relatives which are aimed at helping you. Sometimes, this dream can signify that you are protected from bad influences of your enemies by your own destiny.
To plant an oak tree signifies that you are quite confident at your long term prospects for success in your professional life.
To uproot an oak tree in the dream signifies that some idea of yours will be proven to be false in real life. This might be used by your enemies in order to bring your reputation down.
To pick acorns of an oak tree means that success will be surprisingly easy in your professional life. Oftentimes, this dream also signifies that easy money will be made by using your skills and natural talents.
To climb an oak tree means that your ever-growing ambitions will not be matched by the amount of energy that you will have in the following few months. You might succeed by the standards of others, but inside you might find the success less than fully satisfying.
To cut down an oak tree in a dream signifies that you should choose your friends more carefully as they might get you in trouble.