So I broke the bank 1 coolant drain plug on my 1999 Avalon last summer when replacing the timing belt (it was on too tight). A few months later It developed a small leak from the stuck threads. Added an old blue bottle Subaru conditioner (Holt's Radweld (not available Stateside)) that I saved up for the next coolant drain& fill for my 2001 Forester. I wasn't expecting much, and thought I'd have to spend $$$ getting the bolt drilled out and re-threaded. Fast forward 6 months, and coolant levels holding conpletely steady and the broken bolt thread gaps are sealed completely. HINT: using this might even prevent having to ever replace the radiator from pinhole plastic cracks, or the crimp joint where the plastic meets the aluminum cooling fins). Unlike other gunky stuff, from what I've seen, it will not clog your heater-core either. Around 5 bucks at your local Subaru dealer. They sell Bar's Leak coolant tablets at the parts stores which is essentially the same thing.