Coolant compatibility

[Noah930]

Maybe an odd question, given that so many of us on this board are here because of our air-cooled cars, but I will soon have to change the engine coolant in my DD, a 2008 Honda Civic. The manual calls for the Honda-branded long life coolant. But is it acceptable to use a product like Prestone (their long life stuff)?

[island911]

mixing certain coolants will make for a foamy (or worse) mess.

[SCadaddle]

You'd better sort the HOATS from the OATS when it comes to coolants. My dear friend with the Gates Corporation (belts and hoses) says run away from the "mixes with everything" branded stuff.

As for my late 90's Subarus that are prone to head gasket failure, when I need to change the coolant I visit the local Subaru dealer and pay them about $26 per gallon for the full strength Subaru approved/branded long life coolant. When you look at the 50-50 pre mix auto store stuff at around $16 a gallon it's really a no brainer. Gallons of distilled water are less than a dollar each.

[M.D. Holloway]

Extended Life Coolants (ELC’s) are long life products which have an inhibitor package which is more resistant to depletion and therefore does not easily deplete with time and provide over 4 years of service life. Extended Life Coolants are based on the Organic acid technology (OAT), or Carboxylate technology, which means that it contains neutralized organic acids as inhibitors. ELC’s do not contain Phosphates, Borates, Nitrites and Silicates. However most ELC’s still contain Glycol as Antifreeze.

Tolytriazole is an effective inhibitor for Copper and Brass protection. Sebacic Acid (sebacate) is a commonly used additive in organic acid coolants and provides corrosion protection for Lead and Aluminium alloys. Ethylhexanoic Acid is one of the primary inhibitors used in ELC coolants. It offers effective protection for ferrous components. Mercatobenzo Thiazole is a very effective inhibitor for brass and copper components

Pure Organic acid coolants do not contain any inorganic inhibitors such as Nitrites, Phosphates and Silicates etc. Hybrid or HOAT coolants have been developed to combine the advantages of extended service life of an organic coolant with the benefits of increased liner protection offered by some inorganic additives such as Nitrite.

Hybrid coolants are also known as NOAT or Nitrited organic acid technology coolant.
A Hybrid ELC coolant may therefore have all the organic acid inhibitors combined with Nitrite

As a general rule mixing of different type of coolants should be avoided as much as possible.
Even if the mixing of two different inhibitor technologies does not produce any adverse affects; their mixing will simply dilute the additive concentrations and reduce the long life advantages of ELC coolant. However, many ELC coolants manufacturers have declared their coolants as compatible with traditional coolants; as long as it islimited to occasional top ups. Examples are Caterpillar extended life Coolant. Majority of ELC Coolants and traditional coolants are not recommended by theirsuppliers as mixable with other brands.

[Noah930]

Thanks, Lubey.

[VincentVega]

Zerex/Valvoline carries a line compatible with just about everything. I use Zerex Asian for Hondas.

[Arizona_928]

If you mix the green with the light red. "phosphate free" antifreeze. You will gel it.
Try looking into G12 coolant. They carry it at NAPA, and possibly other chains.

[rusnak]

I read some of the tech articles on Pelican about changing your Porsche's coolants, and came across a comment by Wayne that said he recommends sticking with Porsche coolant, and furthermore, changing it every few years or so. I had come to the same conclusion about the Mercedes, and had been using only Mercedes Benz coolants for a few years in it. The reason is that the cooling system is designed for that type of coolant specifically.

But I have even gone further, to additionally stick with manufacturer hydraulic oils in the Kubota RTV for example, and Kubota brand brake fluid in that same vehicle. The factory shop manual specifically states to use the manufacturer's, fluids for some reason. I don't think it's prudent to question why. Not for a vehicle costing tens of thousands of dollars. Not in my opinion anyway.

Oddly, for the Porsche Cayman, the manual states that the steering system uses CHF 202, a synthetic hydraulic oil. It does not say "Porsche" brand. I found that Napa Auto carries it. And the Porsche manual does not say to use Porsche brake fluid, only DOT-4.

Get a big ol container at Smart and Final, or some supply house. Mix the recommended amount of distilled water and coolant in a separate container. Use that to fill the cooling system. Follow instructions regarding bleeding air out with the bleeder valve.

[1990C4S]

I would minimize the risk and buy the same coolant. I might even get it from Honda.

The added cost is minimal, and you do not want to have a compatibility issue.

If you really want to change, I would flush it with a hose, drain it again, drive with distilled water for a few days, then switch to Prestone green. but make sure you get a very good flush done.

[aigel]

Similar situation on my old Sequoia. Toyota coolant ... never could get a clear answer, after much research, on what to use. So, just always bought the Toyota coolant which I bought online. It is good for 100k miles (timing chain / water pump interval) or your next coolant leak!

G

[cgarr]

I would use what they call for and I am a real aftermarket guy but not so much for coolant, I have pulled a lot of vw's apart with the wrong coolant and the insides are a mess, Long term stay with what they call for, VW's G11 or G12

[stealthn]

You have to wonder if it's formulated specifically for each engine's components, magnesium, iron, aluminum, titanium this and that, etc? I know if under warranty for Porsche, if you use something else it voids your warranty.

[KNS]

Modern engines run at higher temps than they did years ago, combined with how seemingly fragile cooling systems are on some cars I would follow the manufacturers recommendations on coolant.

BMWs are famous for $hitty cooling systems but I've always used the factory coolant and have never had any issues after 12 years on mine.