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MG MGF Technical - Colour of OAT coolant

Hi all

I'm sure I'm worrying about nothing, but:

Post HGF, the nice chaps at Tech-Speed refilled me with OAT. This is a lurid yellow-green colour.

It seems I still have a coolant leak; I'm dropping maybe 500ml every 100 miles or so. Obviously I'm looking to get her back to TS asap to fix the leak, but right now I'm just topping her up every day to get to work and back. My B&G coolant level sensor is both a curse and a blessing...

Anyway, having put a good half-litre of distilled water into the coolant tank over the last week, I figured I'd better start topping up with coolant instead! Partco (= Unipart) are actually based here in Oxford, so I went to them and got 5L of OAT coolant. Bloke on the desk seemed very knowledgeable, and knew that this was the right stuff to go into the Rover K-series.

Anyway, it's brown. Having seen threads here stating that OAT comes in different colours, and being more than a little worried about further diluting my coolant by refilling with water again, I put some in.

The two coolant don't mix. In that, if I look in the tank, I see the green on top and the brown sitting beneath. This is even post-driving to work this am (9 miles). This suggest to me that there's more of a difference than just a colour compound!

The car seems to be running perfectly happily (well, she chugged a bit more than usual for the first ten seconds this morning, but I put that down to starting at -4 degrees...). Should I worry?

Thanks in advance for assuaging my post-HGF paranoia!

J Wakeham

you shouldnt mix OAT with ordinary anti freeze.
also if it's still losing coolant a trip back to Techspeed would be the best thing to do. Dont go risking another HGF, and they did charge you for the work.

So it's probably a leaky hose or something

...check your oil!


I certainly know that I can't mix OAT and non-OAT coolant. TS told me the green stuff they put in my tank is OAT, and the bottle I bought from Partco certainly says OAT on it. They're just... not mixing together!

I suspect a hose somewhere too. There's a coolant spot beneath where I park her oevrnight; central but an inch or two in front of the rear axle. I almost wonder if it's still the same leak that caused the HGF in the first place... Gav id say he'd pressure tested the system, though, and he'd been convinced there wasn't a problem. Odd. Either way, she's going back to TS at the first opportunity!

Re-reading, I wasn't clear above. Obviously I'm worried about the coolant loss, and will get it fixed asap. My question, though, was whether I should also be worried about the differing OAT coolant types.

J Wakeham

Can you mix the blue stuff with the green/yellow stuff???
Bob Millar

Are they both OAT, Bob? If not, then definitely do not mix them.

Even if so, I'm not yet sure! Anyone, before I have to drive home?

J Wakeham

I'll check the bottle as it's in the car but I have the green/ yellow stuff in the car. Always had the same colour. Checked the handbook and it said only use Coolant with the number "xxxx" (x = number I can't remember)

Went to the motor factors to get a bottle to keep in the car. They had some that was "xxxx" but it had some more numbers after "xxxx:xxx" Bought it anyway as it was only a couple of pounds but when I opened the bottle it's blue in colour rather than green/ yellow and I poured some into the white cap to confirm the colour.
Bob Millar

Actually the handbook says that any ethylene based anti-freeze containing OAT is fine providing it does not contain methanol.

Apparently methanol and aluminium don't like each other!!

So Bluecol or the like is fine - no need for expensive XPart stuff. Just make sure you read the label carefully on the bottle.

david stonehouse

the coolants of oat are orange and pink on the k series i am using havoline as suplied by souls off mk
just been done cam pump and timing belt
darren jeffery

On my old mgf (10 years old) I suffered a busted hose and went to the rover/ mgf dealer. The guy sounded knowledgeable and away I went only to find my colour was the flouresent green/yellow and the one he gave me was pink.

Went back next day and another knowledgeable guy on the desk confirmed that need to use yellow/green and not the pink.

I can confirm that newer stuff in my tf is pink. I have always taken the stance that with hgf being common take no chances. Id get back to TS asap


Found similar as Darren said with orange and pink (magenta) when I looked for changing to O.A.T. in last year.
Finally I did in the pink G12 *Glysantin Alu Protect Premium* stuff from BASF.
Not sure about the mentioned green/yellow from Havoline . Could this be H.O.A.T (ZEREX G-05), and should IMO be OK ?

I'd be worried with the brown stuff in yours from the same reason. My be wrong mixed.

This thread was discussed between 24/01/2006 and 25/01/2006

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