The Storm RTR comes with greased diffs. Go ahead and break her in. Unless you have already done your homework on what weights you will be using, I would break it in, run it a while, figure out what weights you want, then fill them up. Remember, only fill the diffs up to the cross pins. You'll see what I'm talking about when you open one up. Once you upgrade to the diff oil you'll see a big improvement in handling. Great choice of buggy too.