Or does it just mean "drain the old stuff, fill with new, and bleed as necessary"?

I make the distinction, and thus ask the question, because I know that in at least two cases -- switching to DOT5 brake fluid, and switching to R134 refrigerant -- you really needed to make sure all traces of the old were out (I've heard of people doing nitrogen purges of brake lines).

Is that actually necessary -- or the use of motor/coolant flush compounds -- when doing a "flush"?

 

Flush means just that, flush it "ALL" out.

 

Do you have a pointer to any detailed instructions about how to do that for various systems? I'm pretty sure from my skimming of RAVE that it just tells you *to* do it, not *how*...

 

What is it you are trying to do?
Send me your number and I'll call you if you have questions.