Does the antifreeze being added after flushing need to be diluted?

The antifreeze should be diluted How much is up to you. Also be sure to configure in the location where you live (hotter, colder) as this also makes a difference I'm pretty sure that antifreeze needs some water to work properly (activates chemicals in antifreeze) If you went 70% antifreeze & 30% water you should probably be fine no matter where you live.

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Ford vehicles come from the factory with a 50 / 50 mix of distilled water and the correct type of antifreeze for the vehicle . Ford states not to exceed 60% antifreeze in the mix