I did it on brake calipers recently to get the bleeders out, and i'm sold on
this method!
You say it's just the heat.....but propane or MAP gas isn't really hot
enough to get the bolt (or in this case the bleeder) Cherry red like you'd
want. I had bleeders completely rusted in place, and i'd do a few cycles of
heating and candle action, and then when i finally did attack them, it was
cold (So no heat), and they came right out.
The wax does seem to get down there. It does seem to work. I haven't tried
it on exhaust components, and like Frank says, if it's corroded badly
enough, nothing will get in there.

That is a tricky job to do.
Make sure noone brakes off any drill bits in one of your heads...... : )

-Craig
'85Westy
'80Convertible Vanagon

On Sun, Aug 17, 2008 at 8:39 AM, Cullen Stewart <cullberly@vermontel.net>wrote:

> I remember reading that. It seems that the heat is what does it, not the
> slim chance paraffin can make it's way to the seized threads.
> ----- Original Message -----
> From: "Allan Streib" <streib@CS.INDIANA.EDU>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Saturday, August 16, 2008 10:39 PM
> Subject: Re: Exhaust studs
>
>
>  Can't remember if it was this list or another, but someone suggested
>> to free a frozen nut, heat it up with a torch and then touch a candle
>> to the threads.  The wax will melt and be drawn into the threads by
>> capillary action I guess.  I'm not sure why candle wax would work
>> better than ordinary oil for this, though.
>>
>> Allan
>> --
>> 1991 Vanagon GL
>>
>