Mk1 antifreeze with silicone hoses...?

I’ve a 1996 1.8 Mk1. The original radiator split recently, and I’ve replaced it with a new aluminium one. At the same time I changed all the original coolant hoses, replacing them with silicone ones from Stoney Racing. ‘SR’ advise that not all types of antifreeze are compatible with silicone hoses, and publish a list of those they recommend. Using this, I’ve bought 10 litres of FL22. However, I’ve a nagging doubt that this may not be compatible with the car itself as I’ve seen forum messages saying it was designed for use in Mk3’s (NC). So, two questions…

  1. Is FL22 suitable for a 1996 Mk1?
  2. To get rid of any trace of ‘what’s in there now’, I need to flush the block - can I do this with tap water, ie: fill the system, run the car and then drain it?

Many thanks in anticipation!

Chris

FL22 is an ethylene-glycol based, proven coolant without, amines and silicates

Most current anti freeze should be compatible with silicone

Coolant Type Silicone Hose Compatibility

Ethylene Glycol (EG) = Excellent
Propylene Glycol (PG) = Excellent
Organic Acid Tech (OAT) = Excellent
Hybrid OAT (HOAT) = Excellent

info is from here - Chemical Compatibility of Silicone Hoses with Automotive Coolants | Venair

I was advised on OAT coolant in a Westfield I built would be an issue, even though the factory supplied silicon hoses and I followed suit with other hoses to not be rubber. I regulary checked them internally and never saw any degradation of the hoses and never seemed to suffer any issues.

Yes, FL22 is suitable to use in a 1996 MK1.

I personally wouldn’t worry too much about flushing the system unless the coolant in there is really manky. But if you want to, then tap water should be OK to use but in a perfect world, distilled water would be preferable.

You’ll only need 5 litres of coolant for a straight drain and refill, as you have 10, you could fill it with 5 litres, plus a bit of distilled water, run it for a bit then drain and refill it with the other 5.

Thanks for your really prompt reply - I’m glad I’m not the only person who’s been reading forums, got confused and been left wondering!

Chris

Thanks! I guess you can’t be too careful - damaging the hoses is one thing, but damaging ‘something else’ could be more of a problem to fix…

Cheers! Chris

Thanks - I think you’ve answered both my and CBRDeano’s questions!

The reason I was going to flush the system is that I don’t know what was used the last time the coolant was changed - it was red, but dirty. So I was going to fill the system, run the car to operating temperature to get the heater involved and then drain it. Apart from getting rid of any old stuff / crud, it would highlight any leaks before I put the ‘real stuff’ in. Yes, I guess distilled water would be best, particularly after having gone to the time and trouble of replacing the radiator, getting it to fit and fitting new hoses.

I’ve actually fitted a Japspeed 50mm radiator which has a higher capacity than standard - I think it’s about 6.5 litres in total (?)…

Very many thanks for your reply which has certainly put my mind at rest about using FL22…

Cheers!

Chris

If the stuff in there is red, dirty or not, then I would flush it. I’d actually drive it for a bit, allow it to heat cycle a few times rather than just let it reach operating temperature, before draining and refilling too.

Okay … out of interest, ‘red’ being…?

I’ll certainly heed your advice though!

Thanks!

Purely because it’s a different colour and mixed with green could look nasty again. Doesn’t red and green make brown?

Yes, ha-ha, I thought you may have been thinking it was an OAT type and incompatible with FL22…!

Cheers!

Robbie, I just wanted to say thanks for the advice you gave about this, and so quickly. It was really helpful - it’s a great service you / the club offers it’s members, and alone is easily worth the subscription.

Thanks once again!

Chris

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