AMSOIL Antifreeze & Coolant Mix Calculator
Calculate the precise amount of AMSOIL antifreeze concentrate and distilled water for any cooling-system capacity at 50/50, 60/40 or 70/30 dilution. Includes the optional DOMINATOR Coolant Boost dose.
Antifreeze Dilution Calculator
Pour the calculated concentrate and water into a clean container, mix, then fill the system. Always use distilled water — tap water leaves scale that kills heat transfer and water-pump life.
AMSOIL antifreeze concentrate
4.0 quarts
= 128 oz · = 0.95 L
Distilled water
4.0 quarts
= 128 oz · = 0.95 L
Optional — AMSOIL DOMINATOR Coolant Boost dose
8.0 oz of Coolant Boost (≈ 1 of 12 oz bottles needed)
Improves heat transfer up to 25% in any glycol-based coolant. Dose is 1 oz per quart of system capacity (4 oz per gallon of system). Optional but highly recommended for towing, off-road, racing and HD-diesel applications.
Quick-reference dilution chart
Quarts of antifreeze concentrate and quarts of distilled water for typical cooling-system capacities.
| System capacity | 50/50 (most climates, freeze ≈ −34°F) | 60/40 (cold climates, freeze ≈ −62°F) | 70/30 (severe cold, freeze ≈ −84°F — max) | |||
|---|---|---|---|---|---|---|
| Concentrate (qt) | Water (qt) | Concentrate (qt) | Water (qt) | Concentrate (qt) | Water (qt) | |
| 1 gal | 2.0 | 2.0 | 2.4 | 1.6 | 2.8 | 1.2 |
| 1.5 gal | 3.0 | 3.0 | 3.6 | 2.4 | 4.2 | 1.8 |
| 2 gal | 4.0 | 4.0 | 4.8 | 3.2 | 5.6 | 2.4 |
| 3 gal | 6.0 | 6.0 | 7.2 | 4.8 | 8.4 | 3.6 |
| 4 gal | 8.0 | 8.0 | 9.6 | 6.4 | 11.2 | 4.8 |
| 5 gal | 10.0 | 10.0 | 12.0 | 8.0 | 14.0 | 6.0 |
| 6 gal | 12.0 | 12.0 | 14.4 | 9.6 | 16.8 | 7.2 |
Antifreeze chemistry — what the dilution actually buys you
Modern engine coolant is a glycol/water blend. The water carries heat, and the glycol lowers the freezing point and raises the boiling point of the mixture. The optimum blend is roughly 50/50 — that's what the OEM and the calculator default to. As you go richer (60/40, 70/30) the freeze protection increases, but heat-transfer drops because glycol is a worse heat carrier than water. Above 70% glycol, the freeze point actually rises again, so 70/30 is the maximum useful dilution.
Why distilled water — not tap
Tap water carries dissolved calcium, magnesium and other minerals that precipitate out under heat and form scale on radiator passages, water-pump faces and cooling-jacket walls. Scale acts as an insulator, drops heat-transfer efficiency, and shortens water-pump life. Distilled water has the minerals removed; it costs about a dollar a gallon at any grocery store. There is no upside to using tap water in a cooling system.
DOMINATOR Coolant Boost
AMSOIL DOMINATOR® Coolant Boost is a wetting-agent additive that improves heat transfer up to 25% in any glycol-based coolant by reducing the surface tension of the mixture and pulling more heat from hot-spot areas like the cylinder head. The dose is 1 oz per quart of total system capacity (4 oz per gallon of system) — the calculator above does this math for you. It's optional but high-value for towing, racing, off-road and heavy-duty diesel use.
Antifreeze & Coolant FAQs
Why does the calculator only let me go to 70/30?
Glycol-based coolants actually freeze at warmer temperatures above 70% concentration than at 70%. 70/30 is the maximum protection point (~−84°F). Any richer mix degrades heat transfer without lowering the freeze point. Most cooling systems should run 50/50; only severe-cold service warrants 60/40 or 70/30.
Do I have to use DOMINATOR Coolant Boost?
No — it's optional. Coolant Boost is a wetting agent that improves heat transfer up to 25%, which matters most for towing, racing, off-road and HD-diesel applications running near the upper limit of cooling capacity. For a daily-driver passenger car in a temperate climate, you can skip it without harm.
Why distilled water — can't I just use tap?
Tap water contains dissolved calcium, magnesium and other minerals that form scale on radiator passages, water pump faces and engine cooling jackets. Scale acts as an insulator, drops heat transfer, and shortens water-pump life. Distilled water has the minerals removed and costs about $1 a gallon at the grocery store — no reason to skip it.
How often should I change coolant?
AMSOIL passenger-car coolant is rated for several years or hundreds of thousands of miles in normal service; AMSOIL heavy-duty coolant carries an extended-life rating for fleet use. Always confirm against the OEM service interval for your specific vehicle, and inspect coolant condition (color, pH, freeze point) at every oil change.
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Independent AMSOIL Dealer #1858536. This calculator is for reference only — always defer to your equipment manufacturer's specifications. Inputs stay in your browser; nothing is submitted, stored or logged.