Prestone Coolant, does it expire ? | GTAMotorcycle.com

Prestone Coolant, does it expire ?

chiller

Well-known member
Site Supporter
Thought I'd ask here and see what I get.

I did a coolant change 2 or 3 years ago and have 1/2 a bottle of premix left from it. I also have a concentrated bottle (non-premix) that has about 3/4 from a different source but still Prestone. Obviously since they aren't full, they have been opened but the caps have been on them and sitting around in a garage for 2 or 3 years.

Does the stuff expire ? I know that brake fluid does if the bottles are opened but I can't find any conclusive proof one way or another on different sites that it does or it doesn't expire.

The Prestone website only has reference to unopened bottles on the site.

Q: What is the shelf life of Prestone® Antifreeze/Coolant?
A: If the product is still in the original sealed container or has not been diluted with water then it has a shelf life of many years.

Anyone have a reliable source ?
 

TwistedKestrel

King of GTAM
Site Supporter
Coolant seems pretty stable to me. Brake fluid goes bad from absorbing moisture, so no problem there. If anything important could evaporate from it, it'd boil off the first time you ran your bike/car. Maybe it could oxidize? Motor oil can, but that takes many years.
 

chiller

Well-known member
Site Supporter
Coolant seems pretty stable to me. Brake fluid goes bad from absorbing moisture, so no problem there. If anything important could evaporate from it, it'd boil off the first time you ran your bike/car. Maybe it could oxidize? Motor oil can, but that takes many years.

Reasonably thinking this out says that if anything, the water might evap out of it slowly and if it does that would leave you with a higher than 50/50 mix of coolant to water ratio. However, if this is the case than its easy you just top up with more water (which you COULD do anyway since most people run the bikes only in warm weather anyway) ... The stuff is so to protect from rust (oxidizing inside the engine and rad) so that should mean that it can't oxidize in just bare air ?
 

TwistedKestrel

King of GTAM
Site Supporter
The anti-corrosion property is an additive, I believe. And you could figure out if the mix was off with a hydrometer... I have never owned one, however. Generally only use premix in bikes and I have hated every car I've owned.

FWIW, if it were me I'd just use it.
 

Riceburner

Well-known member
I'd just use it. Which reminds me...gotta pick up some distilled water to mix with my bottle of old unused coolant to do a fluid swap too.
 

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