I just changed mine to engine ice, as mentioned its not an additive its pre mixed an takes about 3 quarts. I drained the cooling system added distilled water along with distilled vinegar.. ran for about 15 minutes (after it warmed up) shut off then drained added strait distilled water, did the same (15 min) drained then added engine ice. On average it seemed to drop 5-10 degrees never see the 230's most i have seen is 226 when it was at 98 degrees out on new black top at a stand still.