A few years ago I ran up on a great sale (under $5 per gallon as I recall, sale was aimed at commercial accounts) of Peak Long Life 5 year / 150,000 mile concentrate coolant. At the time, with two MCs, 2PUs, and 5 cars that were liquid cooled, I bought 3 or 4 cases. It is designed for all cars & all MCs and all vehicle cooling systems. It is yellow, it is silicate & phosphate free too.

https://peakauto.com/products/antifreeze-and-cool/auto/long-life-full-strength/

Today, checking to make sure it was OK in my Fords (and it is as I thought), I looked it up too and I see in a spec sheet they mention a shelf life of 3 years in an unopened original container, of which I have probably 25 left, though I have sold some of the vehicles and MCs.

So my question is:
How does … a concentrated coolant product …
last longer … mixed with distilled water @ 50/50 or 60/40 in a cooling system …
than it does … in an unopened sealed original container in cool, dark, basement shop storage ????

I sent a query, no answer yet.

I know from past reads here, some of you will know.

Thank You.

Wow! I’ll be watching for a response as well.

I don’t believe it went bad on the shelf, but perhaps some of the anti-corrosion chemicals degrade over time, or have a half-life of some sort.

I’d probably open one, and check the specific gravity. If it checks out, I’d personally probably use it, and just keep a watchful eye by testing it periodically.

I hope someone pops in with the real scoop on this however.

I hope not. I'll post back if I get anything.


I almost think it's a marketing deal.

It could just be somebody didn't do too good a job of proofreading their ads and/or spec sheets. Or, maybe they reformulated during the few years since you bought the original stuff. What is the date of the spec sheet? Does it go back far enough to cover the stuff you bought way back when? Does the label of what is currently available still say Peak Long Life 5 year / 150,000 mile concentrate coolant?

There is a shelf life but it should be longer then 3 years.

I looked it up online, same exact stuff. I bought mine in maybe 2016 or 2017. I'm gonna use it, if still sealed I know it's not contaminated, I can shake it up prior to use with distilled water. It's not likely to develope a charge in the absence of metal blocks or heads or rubber seals, etc. Just a curiosity on my part. Still nothing from Peak.


Later then .... & Thanks

My guess is the additives settle out after a while. Don't know what else it could be, but I are not a chemist.

Well, I'd give the jug a good shake anyway. What settles out will be in the jug if sealed still, and no way it's gonna evaporate still sealed.

Maybe they mean shelf life after the jug is unsealed?

Never did get a reply, but the more I look, the more that seams the only way possible, if not kept in a closed container maybe?

Maybe my question was too difficult?

Never did get a reply.

If your car hasn't exploded in a geyser of steam, that answers that. While I have no idea what any official answer is, if its sealed, I'll use it.

The reason they won't tell you is the same as why Ford will never say that it's OK to use something other than 5W-20...it'll get them in dutch with the gummint. Also, they won't sell as much if you don't keep throwing away perfectly good coolant after only 3 years.

If that sounds bitter and cynical, you're right. Age does that to a fella...

It would be interesting to run a lab test on the coolant but it would probably cost more than you saved on the coolant.

I'd use it without concern. Seen too many vehicles that probably never had a fluid change.

Noticed that some coolants previously rated ASTM D-4985, heavy duty, are now rated D-3306, light duty.

When I replaced the radiator in 2020 in the 2007 Galant I used to have I threw in an unopened bottle of NAPA coolant from 2002.

I've noticed a lot of chemicals in metal containers list the shelf life as 2 years unopened, but have been viable in use.

I would have no qualms using it.

The Pull apart nearby has 'recycled' coolant in milk jugs with a funky brown tinge to it. I would not use that.

Does properly stored, unopened alcohol really ever go bad?

Exactly. Some alcohols get better with age.