Diff oils - Need help, plz look!

[Dafni]

Hey guys, I need your help to clear up some confusion here!

First of all, how do I choose a diff oil weight for my application? In my buggy I tested some combos, but somehow it does the opposite of what I was expecting. For what should I look for? I need suggestions for front, rear and center, because I'm still only beginning to understand these things.

And second: What would be a good oil weight to start on my center diff in the revo (ofna ultra diff) and front or rear (stock gears)

Another thing: I have several different brands of diff oil, and I recently got some UE bottles. They were in the same containers as some oil I got from a german distributor. (probably the same producer) But the labels on them are totally off. The weight numbers correspond in no way. I mean, the viscositiy of a liquid is a well defined number, and it can be measured. So why on earth would companies invent their own scale?

Thanks for reading. If someone could elaborate on this a bit, I would be most gratefull. What oil weight will have what effect on driving characteristics?

DAF