Just built a Cougar SV2, got a question...

[BigJames]

I wondered if someone could help with a noob-ish question?
I've completed the build, but realised earlier that I didn't use the sachet of brown-ish grease included with the kit, during the build.
Should this have been used on the two diff gears? I used the black and clear silicone grease where specified in the manual but I can't find anywhere that mentions the other stuff.

Thanks