I've replaced the water/ethelene glycol antifreese mix to Evans waterless antifreeze in my '87300SDL. I costs about $25 a gallon but I think it is worth it. Since it doesn't boil until 375F, yes three seven five, there is no pressure needed in the system to keep it from boiling. To keep the pressure to zero, just leave the cap loose.
This makes water pumps, hoses, radiatores, heater cores ETC. last much longer because the are not operating under pressure and the waterless anti freeze is not corrosive to anything like a water/antifreeze mix always is. It eliminates the need for frequent anti freeze changes so in the long run may cost less.
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