| Antifreeze % | Freeze Point |
|---|
Mixing Antifreeze to a Target
Concentrated antifreeze must be diluted with water before it goes in the cooling system. This tool splits your system capacity into the right amount of concentrate and distilled water to reach a chosen concentration by volume, so you can buy and mix the correct quantities instead of guessing. The classic starting point is a 50/50 blend.
Why 50/50 Is the Baseline
A half-and-half mix of ethylene glycol and water protects to roughly -34°F while still carrying heat well and resisting boil-over. It is the manufacturer default for most climates. In very cold regions you can go richer, up to about 60 or 70 percent, to push the freeze point lower, but you trade away some cooling performance to do it.
More Is Not Always Better
Antifreeze freeze protection peaks near a 68 to 70 percent mix. Beyond that the freeze point climbs back up and the coolant carries heat less effectively, which can cause overheating in summer. Straight antifreeze actually freezes at a higher temperature than a proper mix, so concentrate is never run neat. Use distilled water to avoid mineral scale.
Frequently Asked Questions
Should I use distilled water?
Yes. Tap water leaves mineral deposits that clog passages and the radiator. Distilled or deionized water keeps the system clean.
Can I just buy pre-mixed coolant?
You can, and then no dilution is needed. Mixing concentrate yourself is cheaper per usable quart and lets you tune the ratio for your climate.
How do I verify the actual mix?
Use a coolant refractometer or hydrometer. These read the true freeze point directly and are more reliable than assuming the poured ratio is exact.