Contour Enthusiasts Group Archives Forums General Troubleshooting How do I determine antifreeze/water % ?

You didn't state your car or engine info so I was assuming v6.
You are right; I4 mtx cooling system has 7 quart capacity therefore 3.5 quarts of 100% anti-freeze would be added if, after thorough flush, block/heater core had only water in cooling chambers.
As stated by others above, only specific gravity will tell you what's actually in there and to be accurate you must drive a while until reservoir and engine coolant have had a chance to intermingle.