cleaning out rear diff

Ive got a quick question. Could i spray brake cleaner into my rear diff to clean it out? I wont be taking it apart, just removing the drain plug and filler plug.

I just drain, then refill. Always loosen the fill plug first before removing a drain plug on a differential or transmission.

It's best to drain the oil after a long drive. It will be a lot thinner, and will be more likely to drain out contaminants too. No reason to flush it with a cleaner, unless you had a bearing that failed miserably. In that case, you need to do a complete tear down and thoroughly clean it.
Like Cusser says, loosen the fill plug first. If you can't get the fill plug loose, don't drain it!

What is the purpose of loosing the fill plug first? Do I just loosen it up a couple of threads or take it out first then drain plug?

If you can't loosen the fill plug, you can't refill the rear. Drain it all out, and can't refill... what do you do now?

Thanks. Simple answer for a simple procedure. I thought it had something to do mechanically. Boy.... Do I feel stupid. I should've stopped for a minute and thought about it.