best coolant choice for iron block, brass radiator and Al trans cooler?

[Ray S]

Which formulation would be appropriate for the sig-pictured 1971 gas RV with iron block, brass/lead radiator, and a new aluminum RAM transmission with heater?
Came with old green of course - is that an issue for the new aluminum lines?
Should I just use Prestone Platinum Univ Antifreeze+Coolant or similar?
Freezing temps AND 100F days are both an issue here.
Re-coring this beast would be $900+ so I want to preserve it.

 

[GRUMPYDUDE2]

Which formulation would be appropriate for the sig-pictured 1971 gas RV with iron block, brass/lead radiator, and a new aluminum RAM transmission with heater?
Came with old green of course - is that an issue for the new aluminum lines?
Should I just use Prestone Platinum Univ Antifreeze+Coolant or similar?
Freezing temps AND 100F days are both an issue here.
Re-coring this beast would be $900+ so I want to preserve it.

​

View attachment 216725​

This: Prestone Platinum Univ Antifreeze+Coolant or similar

 

[Propflux01]

Old green is what I would use.

 

[Jetronic]

I'm in favour of using a coolant that won't create deposits over time, so OAT. Those deposits could reduce cooling system efficiency or stop the heater from working, and you need to keep on top of maintenance

 

[atikovi]

The old green stuff is old tech with low protection. Using it would be like using SD grade motor oil or whatever was used in the early 70s instead of a modern synthetic. Any of the universal extended life coolants would good, Prestone, Peak.

 

[doitmyself]

The old green stuff is old tech with low protection. Using it would be like using SD grade motor oil or whatever was used in the early 70s instead of a modern synthetic. Any of the universal extended life coolants would good, Prestone, Peak.

The Spec. sheets at Zerex suggest otherwise. compare the metal wear rates (green does better with solder):

US_Val_ZXAmerican_AFC_EN.pdf - DocuSign CLM

sharena21.springcm.com

US_Val_ZXOGreen_AFC_EN.pdf - DocuSign CLM

sharena21.springcm.com

This VERY old article from 2004 suggests that conventional IAT "green" coolant protects solder/brass/copper better. BUT, this article is so old I am not sure of its validity anymore: https://www.motor.com/magazine-summ...-not-easy-being-green-or-yellow-or-orange-or/

Finally, here is a recent BITOG discussion on the subject: https://bobistheoilguy.com/forums/threads/classic-car-coolant.352745/

Good luck. It's a very tough decision with all the choices.

 

[jetman]

Dexcool, it is a OAT coolant.

 

[atikovi]

The Spec. sheets at Zerex suggest otherwise. compare the metal wear rates (green does better with solder):

US_Val_ZXAmerican_AFC_EN.pdf - DocuSign CLM

sharena21.springcm.com

US_Val_ZXOGreen_AFC_EN.pdf - DocuSign CLM

sharena21.springcm.com

That says green has a 5 year 100,000 mile service life and the "American" coolant, whatever that means is 5 years 150,000 miles. The extended life coolants say 10 or 15 years and 300,000 or 400,000 miles. That tells you something right there.

 

[wings&wheels]

I would stick w/ original 'green' as it is known to be compatible with solder and brass, neither of which have been widely used in new vehicle cooling systems for quite a while and if it requires more frequent changes, than so be it.

That said, you try and could ask Prestone or Zerex's tech folks. I've had very good results with this approach once you navigate to someone who is willing to talk.

 

[RooflessVW]

I typically use JD Cool-Gard II in anything that has been completely emptied/flushed.

 

[Trav]

 

[burbguy82]

I use Supertech Dexcool because it is cheaper

 

[Chris142]

The old green stuff is old tech with low protection. Using it would be like using SD grade motor oil or whatever was used in the early 70s instead of a modern synthetic. Any of the universal extended life coolants would good, Prestone, Peak.

That old radiator is very expensive to replace or recore. I sure wouldn't put a long life coolant in it.

 

[Ray S]

Nice informative results; is the "automotive" an IOT green or newer OAT?

I have a jug of NAPA green https://media.napaonline.com/is/content/GenuinePartsCompany/889651pdf but MSDS doesn't say re silicates etc.
Main concern is the brass and lead radiator and galvanic corrosion with the new aluminum. To that end, I have considered an anode cap like https://www.northernradiator.com/SHOP_SUPPLIES/RADIATOR_CAPS/SACRIFICIAL_ANODE_CAPS/Z17705

Even without the new lines I would likely stick with green, but IANAE on coolants so have the classic green ones' chemistry changed, like ZDDP has in motors oils?

 

[Ray S]

That old radiator is very expensive to replace or recore. I sure wouldn't put a long life coolant in it.

Yep, replace is impossible/NA. Recore of a 23x26" 3-row is $900 or more not including labor of course. A number of folks in the group have gone aluminum for that reason.

 

[Ray S]

Finally, here is a recent BITOG discussion on the subject: https://bobistheoilguy.com/forums/threads/classic-car-coolant.352745/

Good luck. It's a very tough decision with all the choices.

+1
From https://bobistheoilguy.com/forums/threads/classic-car-coolant.352745/post-6064247 :

old school IAT green (which is low silicate these days)
...
low silicate green coolant doesn’t belong in anything

This^ is what I worry about and why I'd ask here - it's the chemistry wonks that I like to read from.
I did just see this: https://5.imimg.com/data5/VP/FY/MY-...reeze-coolant-concentrate-0-28882-50102-6.pdf which looks promising if one is to believe specs.

Several classic car guys run Toyota Red
...
silicate dropout over time in an engine that sits is the problem

Red also seems viable^ and RVs do sit for months.

Yesterday I flushed with just water until every line ran clear, so now is the time to decide.
On the 413 Industrial the block has petcocks so I'm sure the block and rad bottom are clear. And, the RB industrial blows coolant directly into the heads to keep the sodium filled valves cooler - important since it runs WOT for minutes at a time with manifolds nearly glowing.

 

[Ray S]

Here is a "red" "for Japanese" https://www.nulon.com.au/products/c...ium-long-life-coolant-100-percent-concentrate which specifically says "Red Premium Long Life Coolant 100% Concentrate is not recommended for use in cooling systems that have a copper/brass radiator (in such vehicles, use Nulon LL, which is green)" > https://www.nulon.com.au/products/c...ium-long-life-coolant-100-percent-concentrate with ASTM results.

 

[doitmyself]

Even without the new lines I would likely stick with green, but IANAE on coolants so have the classic green ones' chemistry changed, like ZDDP has in motors oils?

Yes, the IAT coolants now have low silicates vs. the very old formulas. I.E., the Zerex green and G-05 have similar low silicate levels.

My bias would also cause me to stay away from any coolant with 2EHA unless I could confirm all of the engine gasketing, etc. is 2EHA safe.

 

[Ray S]

Yes, the IAT coolants now have low silicates vs. the very old formulas. I.E., the Zerex green and G-05 have similar low silicate levels.

My bias would also cause me to stay away from any coolant with 2EHA unless I could confirm all of the engine gasketing, etc. is 2EHA safe.

Something else to worry about...
ALL gaskets in it are 1971 original or OEM replacements.

I think I'm leaning toward using the NAPA green and getting a sacrificial anode cap.

 

[JHZR2]

View attachment 216753

Agree! Cool Gard II or G05.