It's in the mix….
Have you always wondered if buying premix 50/50 antifreeze is a good idea as compared to purchasing concentrate and mixing yourself? The 50/50 solution provides protection down to temperatures of -34F/-36C. If mixing yourself, you will want to buy a half-gallon of distilled water and add it to a half-gallon of Ethylene Glycol to arrive at the correct concentration. If you chose this route do not use hard water. Also note that Ethylene Glycol is considered an industrial waste, so it must be disposed of properly.
Propylene Glycol in a 50/50 solution protects for temps of -27F/-33C and is considered non-toxic. A 60% concentration, or more Glycol, reduces the cooling system performance since the solution becomes excessively viscous at low temps (hopefully, you don’t need protection down to -63F). To properly check the protection levels of either, use an Optical Refractometer as opposed to a Hydrometer.
Waterless antifreeze is another option. Lookup Evans Antifreeze on the internet for more information.
There are three main ethylene glycol formulations today:
Silicate based – green coolant
Organic Acid Technology (OATs) with no silicate and can last up to 5 years
Hybrid Coolants which combine small amounts of silicates and organics, also in the 5 year range
If Silicates are left in the system, there is contamination build up inside the radiator. Silicate dropout occurs after the coolant is “spent” and the inhibitors drop out of the solution, causing metal components begin to deteriorate. Flushing the system will help remove these particles.