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Discussion Starter · #1 ·
Simple question: why would you dilute Dex-cool antifreeze? According to the back of my Prestone container:

- A 50/50 ratio prevents engine freeze-up down to -34 F and boilover up to 265 F.

- A 70/30 ratio prevents engine freeze-up down to -84 F and boilover up to 276 F.

Why, then, does the container say that 70/30 is the maximum allowed ratio? Is anything above that corrosive or something? Thanks for helping the newbie out.

Edit: while I'm at it, would you recommend using a radiator flushing agent on occasion?
 

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Coolant, a misnomer, does not transmit heat as well as water. They don't recommend a mixture greater than 70% coolant probably because the cooling system won't effectively remove heat from the engine. People have adjusted the ratio of coolant to water for their location and driving habits. For example, if you lived in an area that never saw temps below 40, you don't need as much coolant because it isn't necessary to protect the system from negative temps. More water (distilled water) will allow the cooling system to remove heat more effectively. I think it is recommended that an 80% water 20% coolant is as far as one should go for street use. The system still needs anti corrosion and lubrication properties.
 

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I would not use the flushing agents. I don't have any concrete evidence that they do any harm, but unless you flush several times with water you cannot be sure you have gotten them completely out of the system.

If you don't contaminate the Dexcool mixture between changes with incompatible chemicals and change it at the recommended five-year intervals you should not need flushing agents anyway.
 

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Stick to the 50:50 mix and add in a bottle of DEI radiator relief. Holds my temps very well...Even in the blistering heat. My tahoe temp drops when i move and holds true at 85c in traffic. My v stays at 85c ad drops with a 160F stat. All in all, loving my mix.
 
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