Here is some info. I did not write this but this will get you started.

CAR SETUP STUFF

NOTE that the rear toe in is very sensitive. MAX 3 degrees. More toe in=less oversteer.

Front- thicker gives you less steering responce off throttle and better on throttle "posi" traction pull out of corners because of the even power to both wheels... lighter oil gives lots of off throttle steering responce because there isn't a lot of resistance to how fast each wheel spins but less front wheel bite out of the corners because the power gets thrown to the wheel with the least traction.

Center- thicker gives more 4wd which can give you some under steer on a high traction track because the power to the rear is pushing the front tires (thicker oil will make the rear loose on low traction tracks while on throttle) but great drive with all 4 wheels accelerating the buggy hard... thinner oil will give you a lot of power to the front wheels so it pulls the buggy around on the throttle giving you good on throttle steering but lacks a little acceleration because mainly the front tires are pulling instead of all 4 digging.

Rear- thicker will give you understeer off the throttle because of the resistance between each wheel spinning to the other but if you do break rear traction both tires will be getting a lot of power making the rear of the buggy loose, thick oil can make handling a little inconsistant because of that... thinner oil will give you quick steering because of the low resistance of how each rear wheel spins and it will give you a hard time to break both tires loose because all of the power goes to the tire with the least traction which is the inside tire. To light of an oil can make the rear of a buggy feel loose everywhere.

A good base setup is 5k front, 7k center, 3k rear. Your diff setup probably wont be perfect on your first try so thats why you need a good base. After you drive the buggy and find out what changes you want to make to its handling then adjust it accordingly by using my info above. Diff setup in my opinion is the most important to make a good handling buggy. Tires being second because if your diff s aren't working correctly then a buggy will never handle right no matter what tires you have on. Suspension setup would deffinatly be 3rd most important and its very simple compaired to setting up diff s. Just take your time and ask for advice from the locals at your track.