'90 Mita Anti-Freeze question

[RonHolly]

Drained and flushed the cooling system today and wondering if I put too much anti-freeze back in. (Florida) I guess the cooling system holds 1.6 gallons and I put the whole mix-with-water anti-freeze back into system. Is this too much and should I take some back out? Thanks

[Quicksilver]

Just did mine today, new radiator, hoses, belts and CAS o-ring. I use the same mixture I've been using for 8 years in Florida: 70% distilled water, 30% antifreeze with 6 ounces of Water Wetter, 160 degree thermostat. Getting ready for MATG XXI.

[RonHolly]

I've owned my Miata for about three years and had not done much to the cooling system. It got hot on me and when I opened the radiator it was like dark rusty water. There was a small hose under the intake manifold that had a crack by the snap ring. Cut off end of hose and re-attached. Used radiator flush and installed new thermostat after flushing well. Think I will siphon some anti-freeze back into the gallon jug and add more water.

[MiataQuest]

Hey RonHolly,
You can buy an anti-freeze hydrometer cheap at the auto-parts store.
This will tell you what lower temperature protection your anti-freeze is good to and give you an indication of your mix. For reference -34F protection is about a 50/50 mix.
Too much anti-freeze will make your engine run hot. You might want to adjust the mixture to around zero to -10F for Florida.

In the future, pre-mix the anti-freeze before pouring it into the cooling system.
You can do this by saving the old antifreeze jug.
Take a marker and identify that jug as "premix".
Then you can use the premix anti-freeze for topping off your cooling system as required.

[RonHolly]

Hey RonHolly,
You might want to adjust the mixture to around zero to -10F for Florida.


Thanks for the tips
This morning I siphoned out about half gallon back in the jug. When I get a chance I'll go by AutoZone and let them give me a free anti-freeze check.

[MiataQuest]

You can buy the hydrometer for less than $10

It is worth adding to your toolbox.
Just rinse it good before putting it away.