found this on the citroen c4 forum, may help.
Most antifreeze and coolant products on the market are ethylene glycol based with additives to prevent corrosion, lubricate seals and water pumps and aid in heat transfer to the coolant from the metal of the engine. Antifreeze coolant should typically be mixed with water at the ratio of one part antifreeze to one part water. This gives antifreeze protection down to minus 34 degrees and overheating / boil over protection up to 265 degrees. Do not use pure antifreeze in a cooling system without using at least 30 percent water in the mixture.
Most antifreeze coolant sold in recent years has been the traditional green coolant which has a life span of two to three years or up to 30,000 miles. Green antifreeze contains silicates, phosphates and borates as corrosion inhibitors to keep the solution alkaline. As long as the solution remains alkaline, corrosion is controlled and the cooling system is protected. Over time corrosion inhibitors are depleted and the corrosion protection is lost, therefore green antifreeze should be changed every two years.
Aluminium is especially vulnerable to corrosion and many vehicles have heads, radiators and other aluminium components in the cooling system. If the coolant in an engine cooling system is changed before corrosion inhibitors reach dangerously low levels, corrosion damage is prevented.
Long Life Antifreeze
An alternative to tradition green/blue antifreeze is a product currently used by many vehicle manufacturers. Orange or Red antifreeze known as long life or extended life antifreeze increases the useful life of engine coolant. Long life antifreeze is also ethylene glycol based.
The difference between the two colours is that Orange / Red antifreeze contains a different type of corrosion inhibitor that has a much longer life than silicates, phosphates and borates. Orange / Red antifreeze contains organic acids that protect engine parts from corrosion.
Green/blue antifreeze does not mix with long life antifreeze. Never mix the two colours in a cooling system. The organic acids in orange types will cause precipitation of silicates in the green type and corrosion protection is greatly reduced.
Orange type antifreezes are suitable for up to five years or 100,000 miles. They can also be used in many older vehicles if all of the green antifreeze is flushed from the system and is replaced with the orange / red antifreeze. The lifespan of long life antifreeze is about four years or 60,000 miles in older cars.
If you have doubts about switching from the green type of antifreeze to long life antifreeze, contact you retailer or car dealer and ask about compatibility with your cooling system. You can also contact Tetrosyl by email for further advice and technical support.
The level of protection of the coolant has little relevance to the corrosion protection. An antifreeze tester may show adequate frost protection but cannot test for corrosion protection which is depleted over time.
Change your coolant mix on a schedule based on the colour of the antifreeze you are using. Severe corrosion to engine and cooling system components can occur with resulting expensive repairs.
also on the same forum
One can get very complicated about coolant and I was once told to simplify it into green coolant and pink coolant, the latter being an extended life antifreeze. However, there are intrinsic differences in the constituents of various coolants and their compatibilities with one another.
Types of Anti-Freeze There are three primary types of anti-freeze for your car’s radiator cooling system:
1. Ethylene Glycol/Polyethylene Glycol. Tried and true, this type of anti-freeze is still standard after almost 70 years. Modern ethylene glycol anti-freezes have several additives to protect, clean, and lubricate your cooling system.
2. Non-Toxic Radiator Coolant. This anti-freeze does not contain ethylene glycol or polyethylene glycol (both acutely toxic). These engine coolants are, however, still toxic but only in larger quantities and over longer periods.
3. Extended-Life Anti-Freeze. In most cases, this is simply an ethylene glycol anti-freeze with one or more carboxylate additives to prevent corrosion of the cooling system. These engine coolants should make your car radiator and cooling system last longer.
Common engine coolant additives include: nitrates (corrosion inhibitors, buffers), silicates (corrosion inhibitors, especially for aluminum radiators), carboxylates (buffers, corrosion inhibitors), and borates (buffers).
Never mix different types of engine coolant. You can damage or further reduce your car radiator’s efficiency by mixing the different types. Before you change types, thoroughly drain and flush your cooling system.
The different types - made even more complicated:
OAT coolant (orange or pink) contains no silicates and no phosphates. It's a blend of two or more organic acids, a specific class of inhibitors with slow-acting, long-life properties. Texaco's Havoline Dex-Cool (also sold under the Goodwrench label by GM) was the first example. Prestone and Peak also have introduced OAT coolants that are chemically compatible with Dex-Cool.
Conventional Japanese coolant (green or red) contains no silicates, but has a heavy dose of phosphates and other inhibitors, including a modest amount of one or two organic acids.
Conventional European coolant (blue or yellow) contains a low dose of silicates and no phosphates, but does include other inhibitors, including one organic acid.
Hybrid European coolant (blue or green) is similar to conventional European, but with a much greater dose of organic acids. It's a balanced formula designed to have the silicates provide the primary protection for the aluminum, then allow the organic acids to provide long-term protection.
carl.
Red or Blue coolant?
Linear Mode
