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MG MGF Technical - How much coolant?

My yellow coolant has turned red/brown over the past year due to heavily rotted, mild steel, original underfloor coolant pipes which now weep. So I bought new SS ones and thought about what type of antifreeze to use.
Superplus 3 original unipart seemed best so I went to Halfords. Not much help there -
'Antifreeze is antifreeze mate, its all the same to us'.
'Why have you different coloured containers then?'.
'I've no idea'.
'Do you have OAT?'(derogatory sexual reference perhaps? - he seems defensive).
'Do you have a standard Ethylene glycol based, phosphate free antifreeze?'.
'Wouldn't have thought so'(stood in front of the products).
I didn't have my glasses to read diminutive print for myself and was swayed by his comprehensive, consuming lack of interest.
Off to the ex MGR dealer who has since snuggled up with Renault. Xpart do the stuff at rather a lot for a leaking 1 litre bottle. Chap definitely was interested and informed, phoning an off duty specialist for confirmation but said that they only ever put 3l in to the 10.5l brew for MGF.
All of the reccommendations I have read are for a 50/50 mix, surely this is much more for corrosion resistance than withstanding cold temperatures?
I am uncharacteristically concerned by this apparent conflict.
Anyone have any thoughts out there? I am especially concerned because so many HGFs occur shortly after major surgery involving coolant changes/disturbance.
C.R.B. Simeon

I put standard Ford Motorcraft Super Plus in my daughters car 30k miles ago seems fine. I did give it a very thorough flush.
Ken Waring

You will need 10.5 litres of coolant for the refill. The original OAT was Texaco Havoline XLC but Mobil and just about everyone else does OAT now, just read the label rather than asking a Halfords assistant!
Chris Aplin

Halfords are appalling. Their staff are worse than useless. They do have their own brand of OAT antifreeze in pretty pink - I've seem it. I'm using Unipart yellow/green stuff which is freely available from Partco (branches everywhere).
Mike Howlett

Thanks for the replies.
A very small part of my original query is what type of antifreeze? I figure that after 11 years the internal surfaces are comfy with superplus, why change.
Part of my concern is the c.30% mixture reccommended by a knowledgeable source - I can see definite advantages with a less aggressive mix in old engines. I don't suppose they advise it on the cost/lost profit basis!
Does everybody use 50% as MGR suggested?
What about some of you professionals?
I'll take my glasses next time.....
C.R.B. Simeon

At 50/50 the freezing-point is at its lowest,good if you live up here ! At about 30% the conductivity of the mix ( the ability to transfer heat from engine block to radiator matrix) is at optimum.
Worst scenario is new "green" polypropylene-glycol in 50/50-mix.The heat transfer of that glycol is not very good ,but is not poisionus (sp?) for animals etc.
Thats the reason why it is not recomended for cars with caravans,cars for frequent track use etc.
Knowing the heat problems with the "F" I stay with old etylene glycol of a good brand in a 30-40% mixture. Waterwetter added makes a diff. and is well worth the expence.
Changing to OAT on an old car is not IMHO a good thing to do. During the years the active stuff have developed a protecting layer, all this will be deleted and a new proscess starts all over again with OAT. The "material" for this new buildup is taken from the block,radiator etc.
Why the coolant pipes rotts away in any coolant mixture is another thing, more related to the rather unclever way the electrics are routed in the chassie = electrolysis. / Carl.
Carl Blom

Brilliant explanations Carl, thank you - the bits I understand I completely agree with your assessment(esp change/electrolysis), and the percentage thing explains why a knowledgeable source reccommends 30%. I was contemplating the water wetter anyway - now to find time to get the job done on my daily drive! Thanks,
C.R.B. Simeon

This thread was discussed between 30/06/2007 and 02/07/2007

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