Which antifreeze?

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NormanS

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I'm looking for some advice re antifreeze.

My engine is a Volvo MD22, which of course is really a Perkins Prima, painted with expensive green paint. It's a standard, simple 4 cylinder, naturally aspirated, bog standard diesel, of about 1991 vintage.

It appears that there are various grades of antifreeze, some blue, and some red, and I'm sure having some less obvious differences.

What type should I be using please?
 
I use the antifreeze specified for older engines which is the blue. The red (fluorescent ) is for the new generation engines. I presume that the red antifreeze may contain chemicals that could damage certain parts of the engine (rubber seals??)
 
If the OP won't mind a related question - Can you put too much in? I can't remember how much I put in at spring recommission and wanted to put more in - how much is too much (percentage wise) on a 1977 Thornycroft 235 with wet liners?
 
NormanS said:
I'm looking for some advice re antifreeze.

My engine is a Volvo MD22, which of course is really a Perkins Prima, painted with expensive green paint. It's a standard, simple 4 cylinder, naturally aspirated, bog standard diesel, of about 1991 vintage.

It appears that there are various grades of antifreeze, some blue, and some red, and I'm sure having some less obvious differences.

What type should I be using please?
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There are basically two types of antifreeze.

The conventional low silicate type ( sometimes called inorganic acid technology) is used in older engines

The "advanced", longlife, , "Organic acid technology", or OAT, type used in engines more recent than about 1994 ( and i think all Yanmar engines)

The colours can be a bit confusing ! Best go by the description and ignore the colour.

The two types must not be mixed. The corrosion inhibitors are different and not compatible with each other. (although it is possible to buy a universal topup mix)
 
Thanks for all replies. I now understand a bit more.
My present antifreeze is the "old" blue type, so I'll just stay with it.
I see that I can get it on-line for approx half the price of a well known highstreet car parts shop.
 
nigelmercier said:
If there is any doubt, can either be used in this type of engine if the system is drained?

I'm also a bit concerned that my last top-up could have been the wrong type. I didn't do it, but the guy would have bought the cheapest!
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It's compatibility between the inhibitors and the materials in the system that's the problem I think. I may be wrong but I am under the impression that the OAT types are not compatible with copper bits and pieces. Modern car radiators are aluminium with plastic header tanks but I am not sure if the rads have to be aluminium because copper is not compatible with OAT or if rads are aluminium now anyway and OAT is used because aluminium rads are not suitable for low silicate type antifreeze.
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Dunno what I should have put in my oldish car with the new aluminium rad!

Could well not make much difference to boat engine installations although it would be interesting to know why Yanmar ( i think its Yanmar ) specify OAT
 
Lazy Kipper said:
If the OP won't mind a related question - Can you put too much in? I can't remember how much I put in at spring recommission and wanted to put more in - how much is too much (percentage wise) on a 1977 Thornycroft 235 with wet liners?
Click to expand...

Yes you can put in too much. Firstly the heat capacity of pure glycol (the key ingredient of antifreeze) is much lower than water, so pure antifreeze is less good at removing heat from your engine. Secondly pure glycol has a higher freezing point than water glycol mix (-12C compared to -34C for a 50/50 mix). This is why engine manufactures tend to specify 50/50.
 
andrewbroadbent said:
Yes you can put in too much. Firstly the heat capacity of pure glycol (the key ingredient of antifreeze) is much lower than water, so pure antifreeze is less good at removing heat from your engine. Secondly pure glycol has a higher freezing point than water glycol mix (-12C compared to -34C for a 50/50 mix). This is why engine manufactures tend to specify 50/50.
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Exactly so, and why Webasto specify a 25% mix in the wet systems, too much glycol and the heat transference to the matrix, calorifier and rads suffers noticably.
 
nigelmercier said:
If there is any doubt, can either be used in this type of engine if the system is drained?

I'm also a bit concerned that my last top-up could have been the wrong type. I didn't do it, but the guy would have bought the cheapest!
Click to expand...

My understanding is that some of the OAT type should not be used with copper/brass. Modern cars have replaced all that with ali or plastic.
For a VP engine of a few years age the traditional type - which will be the cheapest* - is the right choice.

* unless it says Volvo on the can :rolleyes:
 
VicS said:
It's compatibility between the inhibitors and the materials in the system that's the problem I think. I may be wrong but I am under the impression that the OAT types are not compatible with copper bits and pieces.

### SNAP

Modern car radiators are aluminium with plastic header tanks but I am not sure if the rads have to be aluminium because copper is not compatible with OAT or if rads are aluminium now anyway and OAT is used because aluminium rads are not suitable for low silicate type antifreeze.

### All the traditional (IAT) ones I've seen for a long time say suitable for aluminium.

Dunno what I should have put in my oldish car with the new aluminium rad!

### Traditional i would suggest.

Could well not make much difference to boat engine installations although it would be interesting to know why Yanmar ( i think its Yanmar ) specify OAT

### I think VP do on newest ones too
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To confuse it further you can get "hybrid OAT" which is supposed to be OK with everything and even miscible with all types!

I'm sticking to IAT in the boat.
 
Troubadour said:
To confuse it further you can get "hybrid OAT" which is supposed to be OK with everything and even miscible with all types!

I'm sticking to IAT in the boat.
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Yes I know there are Hybrid types. I thought for certain vehicle makes rather than as a general alternative... no idea what they are they. Did not know they would mix with either of the other two. I think I would have kept it separate too.

Did not mention the hybrids... did not want to confuse the issue further.
wink.gif
 
nigelmercier said:
I wonder if it is possible to buy just the inhibitors, I don't need antifreeze. Fernox perhaps?
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Yes, I use them quite a bit in wet heating systems, a good central heating or plumbing shop can advise and supply one appropriate to the materials in your system. Sentinel make various types for corrosion and scale protection.
 
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