"OAT" Antifreeze - can I dilute it?

[Avocet]

Just about to change the wife's antifreeze (well, the stuff in her car at any rate!) but it uses this tricky new "OAT" stuff. I only seem to be able to get it ready-mixed 50:50 with a claim that it protects down to -34 degrees C and a warning not to dilute it.

Whilst that degree of protection would be handy if I lived in Moscow, I don't! So the question is, can I dilute it further, or do other bad things happen? Also, will those little antifreeze testers (the pipettes with the floating balls in them) work with this stuff or only with glycol antifreeze?

 

[mfarrow]

Most of the 5-year stuff is OAT.

What car is it? Make/Model/Year/Engine.

You should be able to get it concentrate.

 

[Burnerman]

Dilute with water as you wish, don't mix with glycol stuff and all will be well!
I don't think the cheapo yesters work with OAT liquids unfortunately.
John

 

[JohnD]

what colour is OAT?

 

[Avocet]

Thanks All,

It's a Nissan X-Trail 2.2 Diesel (T30) on a '56 plate. It's the YD22Eti engine I think.

The stuff in it is supposed to be OAT (and has been in there from new). It's green. The stuff in Halfrauds is red (but still OAT).

 

[JohnD]

Green is usually Glycol (which is cheaper)

The red stuff is more expensive.

Did you buy the car second-hand?

 

[Belle427]

personally i dont mix different colours, i would drain as much as you can out and refill with new.

 

[Burnerman]

Nissan have used their 'own' green antifreeze for many years now, and it is OAT.
If you want to change it for another make, thats fine - but there will be quite a bit of the old stuff trapped in the heater matrix etc so a bit of flushing is needed!
Usually replacement 5 year OAT is red these days.
John

 

[Avocet]

Thanks all, that's useful. yes we got it second hand but it wasn't old enough to have needed an antifreeze change when we got it and there was nothing in the service history. Also, it didn't smell "glycol", if you get my meaning. Pretty certain it was OE. I drained the radiator and, sure enough, only about half the quoted cooling system volume came out. so I assumed the rest was in the block / matrix. I refilled with water, ran it and dumped the coolant again (still green) and then did it a third time (less green, but still a definite green tinge!) Surprising just how long it takes to clear it!

As an aside, does anyone know if those little "pipette-type" antifreeze testers work with this new stuff, or only for glycol?

 

[Burnerman]

The pipette testers are only for glycol stuff......presumably they work on specific gravity of the solution.
John

 

[Stivino]

I always thought that all types of antifreeze contained an ethylene glycol base.
i.e. OAT is ethylene glycol with Organic Acid additives.
The dye (usually red) is used on OAT and HOAT types to differentiate it from standard ethylene glycol.
QED?

 

[Avocet]

Don't know. I was under the impression they were fundamentally different (and incompatible) chemistries.

I've answered my own question on the tester front though - the Halfrauds website says it's cheapie testers are suitable for both:

http://www.halfords.com/webapp/wcs/..._productId_159068_langId_-1_categoryId_255224

 

[Burnerman]

At least we've got somewhere - thanks to both for that!
I've heard of mixtures going gelatinous, but personally I've had no experience of that one. Maybe the advice not to mix is purely financial rather than chemical - who knows?
John

 

[Stivino]

Maybe it's compatible with all types because they all have the same base (Ethylene Glycol) and that's what it's measuring?
It should be easy enough to find out. I feel a bit of Googling coming on.

 

[mfarrow]

Yes, that's correct.

There are three main components to the coolant in your car:

- Water (obviously)
- Anti-freeze (usually alcohol)
- Corrosion inhibitor

Cheap testers that rely on floating balls only cover the anti-freeze bit, and were most helpful when cars used to leak regularly.

The corrosion inhibitors are 'hidden' to these testers, but slowly degrade over time and will require replacement (typically after 5 years).

Most manufacturers now state the coolant they fit will last 10 years, which is the expected life of the car. I've not seen anything to suggest they have actually filled them with corrosion inhibitors to last 10 years though, and Haynes still recommends an interval change of less than that.