Front and rear Diff, diff fluid or grease?

[Faxx21]

Ok, I am a little confused here and would appreciate any information you guys can give.
I have a Slash 4x4 PE and am running the center Diff and stock ESC / Motor with a 2s Lipo.
The front and rear diffs had “balck grease” in them but as that wears and leaks out, what is the best replacement? The grease or a Diff fluid? And where and how do you apply it? Do you just put it in to the diff housing or on the Ring and spider gears too? If the diff fluid is the best option what’s a good starting point for the weight? Same question goes for the center diff. Since the fluid/grease is not really sealed in the front and back is it smart to put a piece of electrical tape over the bottom of the housing to slow it down from leaking out? On my Slash 2wd there was a piece of tape that helped keep things out on the bottom of the trans case. I am wondering why the bulkheads are the only thing in place to “seal it up” on the 4x4?
Thanks for any info you can give!

[aussiek2000]

Clean out the diff housing and internal gears with some motor spray/brake cleaner/carb cleaner. Then put diff fluid back in. 15,000 weight front, 7,000 weight rear seams to work pretty well. Make sure that the 2 blue o-rings are intact and the black diff seal is good before bolting it back together. Use just an all-purpose grease on the ring and pinion gears.