1st noticed a low level (idiot light) months ago. Added distilled water then. Did not see the leak, just thought level was a little low. Now it's definately leaking and I added ~3/4 of a gal of distilled water Tuesday. Light back on today so I need to add more. Didn't want to add more water only - afraid it may boil. Probably used ~ 1 gallon of water so far and probably needs another 1/3 gal now. Not sure when new tank will arrive. Don't trust idiot light and I'm checking every day. Just want to add some coolant that won't mess anything up with my existing coolant. Thanks for any suggestions on this.