Ok, I took out the drain plug on my rear axle and what came out was a bit of a suprise...

White, thick honey-like "fluid".

Very similar to melted Bit-o-honey candy.

Ummm... is this bad?

I am letting it drain over night, and will fill with cheap fluid, drive for a while, then drain again... re-fill with synthetic/limited slip additive.

I wondered why it had a strange whine in the back.