One more thing... I really suggest using only distilled water, or at least filter your tap water through something fine meshed... this way you can avoid any sandy sediment which could get into the coolant if your well water or city water is not perfect
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As far as how much coolant these hold... lemme check the spec book...
2.5L ATX = 8.6L (9.1 qt.) = 2 Gallons + 1.1 quarts.
2.5L MTX = 8.4L (8.9 qt.) = 2 Gallons + .9 quart (~3.75 cups approx).
2.0L ATX = 7.1L (7.5 qt.) = 1 Gallon + 3.5 quarts
2.0L MTX = 6.6L (7.0 qt.) = 1 Gallon + 3 quarts
* to convert to imperial measure, multiply US quarts shown by 0.83
