Coolant formulations

[fritz_269]

Old PH post (written by fritz_269):

Originally posted by joncash
The important thing w/ antifreeze is that you don't mix types. That's where you run into problems. But the only two "types" of antifreeze is the red/orange stuff and the traditional green kind. They perform the same way (raise the boiling point and prevent corrosion) but the orange stuff takes longer to break down, and doesn't have to be changed as often.

Everything in your post is right on, except for this point. In some sense, you're thinking on the right track, but there are a couple very important distinctions to be made with different coolants.

One of the three primary jobs of any coolant is to inhibit corrosion; they do this through the addition of chemicals that bond to the metal of the coolant passages and form a protective layer. These inhibitors are most often found in the form of sodium salts: sodium nitrate, sodium tolytriazole, sodium molybdate, sodium borate, sodium phosphate, sodium benzoate and sodium silicate.

Classical coolants mainly used sodium borate to achieve good rust inhibition on iron blocks. But as aluminum made a debut, mainly in heads and radiators; it was found that the borates do a poor job of protection, so silicates were added to the mix.

Silicates are cheap, and they protect aluminum from corrosion very well, but they have some pretty major disadvantages:
1)Silicates tend to gel and settle in the coolest parts of the cooling system, causing radiator plugging and overheating.
2)Silicate inhibitors are difficult to stabilize and, therefore, limit coolant shelf life.
3)Silicates tend form small crystals that are extremely abrasive on soft rubber seals, particularly in the water pump. Borates also have this same problem.

For these reasons - it is extremely important that you use a coolant that does not contain silicates in your all-aluminum Honda engine. I guarantee that your water pump will leak if you do.

Honda brand coolant uses a propriatary organic compound for corrosion inhibition, they use no borates and no silicates (I think no sodium salts at all, except perhaps phosphate). Honda coolant will not gel, it will not de-stabilize (it lasts a lot longer!), and it will not erode seals. It's also already premixed 50/50 with distilled water.

You can get lots of other coolant brands that are "silicate-free" but make damn sure they say that clearly! "Low silicates" or "aluminum compatible" is not enough! If it's not already mixed, mix it 50/50 with distilled (de-ionized) water. But the other brands may (or may not) have borates, nitrates, and all the other sodium salts in various concentrations - we'll never know as they are not required to publish their formula.

One final point - coolants are dyed by the mfg. to be any color they want! The pure ingredients (mainly just ethylene glycol) are a pretty much clear solution, and it's dyed so you can identify it when it's leaking. The contents of the coolant have absolutely no bearing on it's color. Don't ever use a coolant just because it has the 'right' color, and don't ever mix brands of coolant, no matter what their color!

I'm still using the factory-supplied coolant in my '98 Prelude (green!). I'll probably stick with the Honda coolant for the life of the car; as I only need to replace it once every 45k mi the cost really isn't very large. I think that Prestone and Texaco make decent silicate-free coolants if you'd prefer. And just a little side note: the new Porsche Boxter has a lifetime coolant from the factory. Unless you spring a leak, you never have to replace it. You can bet your bunny that there's no sodium salts in it!

[hondabitch]

DO NOT PUT DEX COOLANT INTO A CAR! dex coolant only has to be changed at 100,000 miles. putting dex coolant in a car with regular green antifreeze with kill you engine and radiator!

[VTEC_boi]

Originally posted by hondabitch
DO NOT PUT DEX COOLANT INTO A CAR! dex coolant only has to be changed at 100,000 miles. putting dex coolant in a car with regular green antifreeze with kill you engine and radiator!

Why?

[fritz_269]

Dex coolant is the brand name for Havoline's silicate-free long-life coolant. It has an excellent reputation and it uses a similar organic corrosion inhibitor to the Honda OEM coolant. It is now OEM on nearly every GM car.

There is also this huge myth that you cannot mix different colors of coolants. This is utterly false. Once again, the color of the coolant has absolutely no bearing on it's composition. You can mix them all you like and you will not damage your engine or radiator. The only warning is that if you mix more than 10% silicate-type coolant with an organic-type coolant, you must follow the replacement schedule of the silicate-type coolant i.e. you don't get the long-life benefit of the organic coolant.

The mixing problem only arises from mixing a chromate-containing propylene glycol (PG) coolant with any ethylene glycol (EG) coolant. You end up with a chromate hydroxyl sludge that will clog radiators and engine passages. But AFAIK, only two companies currently sell PG based coolants: Sierra and AMSOIL. PG is slightly less toxic than EG, but does not cool quite as well. IMO, just stay away from PG coolants and you'll never have a problem; stick with OEM Honda coolant, and you're even better off.

hondabitch - read the thread above more carefully before posting bogus info.