I want to change the diff fluid in my Tmaxx. The diff's aren't sealed so what do I do to seal them? What I mean is, I don't want them to leak, so what do I have to do to stop them from leaking? A dude at the LHS said to use silicone sealant to seal the diff's. Is this good advice and if so, what kind of silicone sealant should I use?