Hey mattyb13 a good start for that buggy all around for diff fluids is 7000 in the front diff 5000 in the center diff and 2000 in the rear diff. all you have to to do is simply pull apart the diff clean out all grease or old fluid and fill it up with the new stuff. you should change out your fluid ona regular basis as it will leak out and or evaporate probably every couple of weeks depending on how much you are going to be drivng. also since you will have those diff apart you should consider switching over to our new and improved cross-pin diffs they provide better handling and over all power in the turns...