When you say the "fuel filter housing" is leaking - can you explain more about what you are referring to?

In your car I think there are two fuel filters. There is an in-line plastic fuel filter down pretty close to the driver's side motor mount. And, there is a spin-on type (although it does not spin on, but is held on with a bolt) that is a metal can design.

If you are leaking from the plastic filter, then I think you are probably right, it has cracked from water in it freezing. If you are leaking from the metal can filter, tell us where? There is a fuel return line from the injectors (the same type of line loops from injector to injector, and then finally from #1 injector to the fuel filter support bracket. This should typically be a cloth-covered rubber line. Those lines go old and bad all the time. If it is just damp there it is no real short-term problem. Longer term you'd want to replace with new injector return lines.

Also, you should be suspicious of the strength of the anti-freeze (as I know you already are in fact). It is well worth having one of those cheap float type anti-freeze testers to gauge the strength of the stuff. -25 is what I'd call "severe" conditions. I'm a little worried for you if you have not verified the anti-freeze strength. I hope it at least does not look diluted with water.

Ken300D