That's what diffs do, but not too much- sounds like you need thicker oil. The whole point of a front or rear diff is to allow one wheel to spin at a different rate to the other, so that it works when when going round a corner, and the same goes for the centre- allows the front and back wheels to...
Generally you have a different weight for each different diff's- as it changes the way it drives. Here is a good site (The bit on oils starts at 4.2)
http://www.neobuggy.net/the-setup-guide/differentials/
It's really down to personal opinion, you have to test yourself which you like the best. If you want you can just stick with the stock weights for your vehicle. :)