Antifreeze half life

It doesn't lose the cooling properties it loses it's lubrication abilities. That is why you lose water pumps when using straight water. Just like people thinking oil breaks down. It does not, it gets dirty and the additives are what break down.

As for the time frame, just change it at recommended intervals. Personally for me it is once a year. For my boss it is when you lose a hose and dump all the coolant.

Over time antifreeze becomes acidic and combine that with at least 2 different metals in the cooling system you now have basically battery acid.

 

If you use red, which is what you should be using you should be good, with green you need to add SCA's

Mobil Delvac Extended Life Coolant/Antifreeze is formulated with organic corrosion inhibitors to provide total cooling system protection for 1,000,000 miles of on-road use (8 years or 20,000 hours of off-highway use). Since the organic corrosion inhibitors do not readily deplete, Mobil Delvac Extended Life Coolant/Antifreeze eliminates the need for Supplemental Coolant Additives (SCAs) as required when using conventional coolants.

 

There's test strips you can buy to test the coolant.

I ditched the green and went with Peak Final, red stuff - lasts half a million miles or so and handles up to 20% contamination if you have to add water or other products in a pinch.

 

In a pinch used coolant is ok to reuse but with a new radiator the mfg usually wants you to flush the system and use new coolant for warranty purposes.

 

Anti-freeze / coolant used in most on-road engines is made from two basic materials. Glycol and Water. This basic mix really does not "wear out". What does " wear out" are the additives used to prevent corrosion and scale.

The additives don't really wear out, they are consumed as they do their job.

The additvies can be replaced or "extended" by adding them to the system. Some systems have a filter unit that has a block of these built into them. Another method for replenishing the additive package is liquid product marked as SCA coolant extender.

Most engine coolants manufactured today should last up to 500K miles or 5 to 6 years. this is based on the system never being opened and the labratory world, not real life.

Basically, your coolant should last quite awhile. The best thing to do is test the coolant on a regular basis. Test strips and kits are cheap. Testing everytime you do PM is a good idea. the strips will give a general overall condition, the advanced kits can go as far as measuring glycol to water ratios and more.