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Hi, I recently bought a 94 Deville. I noticed in the coolant tank it was too empty to see any coolant inside. The car doesnt overheat but I want to make sure that its good. Should I just add some coolant or should I drain it and refill it since im also not sure of when it was last changed. any help would be appreciated.
 

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First, with the engine cold, remove the radiator cap and inspect the remaining coolant. It should be red/reddish orange(Dex-Cool), not yellow/green, and should not have any oil contamination. It's also supposed to contain a special supplement to seal any porousity/gasket leaks. Use an automotive hydrometer to measure specific gravity,(temperature range),of coolant. Finally you'll want to check the level of salicillates and other disolved solids, and run the coolant through a reverse osmosis recovery device(coolant cleaner). Or you can simply do what I did when I bought my 4.9L 94. Drain it, take the old coolant to a shop or store that recycles it. flush the system and refill it with equal parts Dex-Cool approved coolant and distilled water and add two tubes of Bars Leaks Golden Seal or three of the bars leaks gold tablets, or a five pack of the GM (expensive) coolant supplement tablets. Do not use any metallic coolant additive. Your coolant level was low for a reason, It went somewhere,. Either on the ground, into the oil, or out the tailpipe.
 

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1996 Deville (sold), 2000 Mustang GT
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If you don't know when the coolant was last changed i highly suggest that you flush it and refill with new coolant. The correct coolant level is 2 inches below the base of the fill neck on the overflow tank. I don't know if you've got the 4.9L or the northstar but it is crucial to change the coolant every 2 years, the northstar is extremely prone to headgasket failure, the 4.9L, not so much, but still very important.
 

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Discussion Starter #4
thanks for the help. I can see some coolant at the bottom of the tank and it looks dark. I think that im gonna flush it and refill it how you said rusty. But how do I flush it? In my previous car that was a dodge dynasty I just unscrewed a butterfly screw to drain it thanks in advance
 

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White Diamond '03 DHS (with DTS floor shift)
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When in doubt, change it. The '94 uses green coolant, not orange Dex-Cool. It should be changed every 2 years. The GM sealant tabs will give it a "rusty" color.
 
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