Hello, I'm Jason. I will do my best to answer your question quickly and accurately using the information you have provided.
You can bypass the heater core at the firewall by installing a u-shaped pipe so that it just recirculates back into the engine
but without doing that, it will still leak
I also do NOT recommend any sort of additive to stop the leak
I gather that means there is no heater control valve on this car that shuts off flow to the heater? I'm leaving on a trip soon, and hate to spend $1500 - $2300 (dealer estimate) to replace the core. I might get it done when I get back because they want a week to replace it.
correct, heat flow is controlled by an air flap inside the car
there is no water valve of any sort
Do you feel I should not drive it on a long trip without replacement?
if it's leaking currently, without a bypass, I would hesitate to drive it
Right now the leak is not noticeable. I add coolant about every 4-6 months.
oh, that's very minor
that wouldn't concern me greatly
Thanks Jason. I have great AAA coverage, so I'll just keep a close eye on fluid level during the trip.
ok, sounds great. Glad to help