>> * Anode/electric-based rust stopper. I forget the brand, and it seems
>> like black magic to me (another round of google searching in my
>> future...). But ... now that I'm listing stuff out I do remember
>> re-connecting a loose cable to this device the first day I began
>> diagnosing the headlight problem. I'll try to figure out how much
>> current this device draws.
>
> Occam sez...you hooked this thing up, and a week later your battery was
> drawing flies.  Coincidence?  Perhaps.  But if you want to shave with his
> blade, unhook the bloody thing and see what happens.

I replaced the two burnt out headlights and the new ones work just
fine. I'm going to say it was just coincidence that they both burnt
out at the same time or that it was due to that one slightly loose
connection between the low beam relay and low beam circuit. Or perhaps
one burnt out and I just didn't notice it because they are such bright
bulbs.

Secondly, there doesn't appear to be a short in the electrical system
(whew!). My battery retained its charge of 12.6V over the past few
days while disconnected, so the battery itself appears to be OK.

Today I got a decent digital multimeter and checked the current in
series between the negative cable and negative battery post and found
a current of 70mA. I then disconnected the "snake oil" rust-prevention
system and the current dropped to 28mA. I'm assuming it is that system
that is discharging the battery excessively and since it doesn't do
any good, I'll be removing it eventually.

Thanks to everyone for their advice, diagnosis help and whacks with
the clue-stick. Next project: moving the oil cooler to the passenger
side D-pillar for better air flow.

Luke