Hondo

1970 Rallye 350 I just had the radiator rebuilt and was wondering how what mix to into it.?

Thank you in advance.

Vintage Chief

In general, in moderate/temperate climates you'd be fine w/ a 50:50 mixture of (antifreeze:water) - i.e. a climate where the temperature falls below 32*F on occasion and for a limited time (several days duration maybe several times/winter). If you resided in a climate where temperatures fall below 32*F for extended periods of time (i.e. one month and/or longer) you'd prefer perhaps a 60:40 ratio. Extreme cold weather climates which remain well below 32*F for the entire winter and often remain below 10*F for an entire month, you'd probably be better served w/ a 70:30 ratio. The engine has to have coolant, but how much antifreeze is required is best decided upon based on the ambient temperatures of the region. I've owned vehicles in California which ran absolutely fine w/ no antifreeze at all & I've owned vehicles in the Northern Plain states where coolant could freeze solid overnight if is wasn't tendered with a minimum of 50:50. There's no dead-fast one ratio fits all cars - the ratio is determined by the ambient temperature you'll be driving your vehicle.

oldcutlass

A 50/50 mix is good to around -34/-38F which fine for almost anywhere.

Hondo

Thank you Norm

ignachuck

I agree with Eric.

redoldsman

Prestone and most other antifreeze manufacturers now sell a 50/50 mixture. They are getting a pretty good price for water though.

OLDSter Ralph

X 2 This is correct !

droldsmorland

Always use the premix. Never add tap water to cut the coolant...always distilled.
Do a complete flush on your system to include the heater core.
Now that you have a fresh start buy some of the coolant test strips and test it annually.
Once it starts to go from PH to Acidic time to change it again.
Its like brake fluid it should be part of your service regiment to change & flush every 3-4 years.

oldcutlass

No its not like brake fluid, the standard replacement interval for ethyl glycol is 10-12 years for these old cars.

Sugar Bear

Anti-freeze does not transfer heat well. Use the chart on the back of the bottle and use enough to gain freeze protection for the extreme cold temps where the car will be located. Anti-freeze also protects against corrosion so use at least the minimal amount needed for that even if you lived in the tropics. In short you need enough protection from both freezing and corrosion in your climate, more than that causes unnecessary diminished cooling.

Good luck!!!

droldsmorland

I dont know about you but I dont have a lab in my garage to test my tap water for solids.
Most of our nation's tap water inherently has impurities such as lime, sulfur, iron. The premix and distilled H20 are closer to100% pure. Much safer.

If you want to keep the solids (scale rust etc) to a minimum in the bottom of the cooling system its wise to change it at 3,4,5 maybe 6 years tops depending on your retentiveness, This allows you to flush out said solids. You can filter the coolant and reuse it but it's much easier to simply drop flush & refill.

I say 3 because if you are like most of us by saying 3 it will be another 2 by the time you get to it...5 which is good.
These cars sit more than your daily driver. This gives things a chance to settle out and build up harder. This is just MO, do whatcha want.

You can flush the core separately. in fact, I recommend it. When it's hooked up to the system it's so far down the pipes that you rarely get all the sediments to move...thus the reason for more aggressive coolant service schedule, Careful with the core. The crud could be sealing up the holes. Then the MAWs will getcha.

Hondo

Thank you droldsmoreland

Lonnies Performance

As stated above, only use a little stronger mixture than you need for your climate.

Yes change it every 5 years even if it looks like new... it isn't that expensive & is easier than changing a heater core or gaskets.

Also if you want to mix your own, distilled water is cheap at the grocery store so you can save a little over the premixed stuff...
In theory 2 gals of premix should only cost about $1 more than 1 gal of full strength, but that's not the case.

My 442 ran typically hot even with a 4 core, so I had a weak mix for the summer & a 50/50 mix for winter storage.
It made an approx 15 deg difference between a 30% & 50% mixture on a hot summer day.

olds 307 and 403

Even up here we only run 50 to 60%. I usually run around the -40 mark on the tester with no issues. I have been mixing it with the deionized water, supposedly the stuff to mix it with.

Weezer

HOWEVER... be careful that you don't buy the distilled that has added minerals for taste! This was a WTF moment for me at Wally-World recently, since I buy distilled water for my CPAP. I will never understand why a bottler would add minerals to distilled water, totally defeats one of the main purposes of it.

rustyroger

I wouldn't sweat over tap vs distilled water unless your cooling system needs frequent topping up. Even then I'd sweat over why it needs topping up and fix the problem.
The tiny amount of impurities in tap water won't do any measurable harm, there will be only a finite amount in the cooling sytsem, it won't increase over time if it doesn't leak.
I concur with most that a 50% mix is all any sub arctic car should need, but it should also be the same for equatorial cooling systems for the corrosion and electrolytic erosion inhibitors antifreeze contains, particularly if there are alumin(i)um components like the water pump or manifold in the system.

Roger.