Engine light ON after topping up coolant!

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I spent the last half hour researching this.... as one does
:D

Bizarrely there's no definite answer.

Tap water
Softened water
Demineralised water
Deionised water
Distilled water

For each one you'll find experts that say that you should use it, and experts that say that you shouldn't (I have disregarded forum posts, of which there are many).

If I had to go by 'ask the audience', then I would use Deionised water because it has the highest ratio of approvers-to-disapprovers compared to all other types of water.

If I went by logical analysis then I would go with Softened water, because it seems like the best water for the cooling system. Though you can't buy it at your local petrol station of Halfords.

very true, it's very difficult to find an definitive answer regarding this stuff.
one thing that i have always heard from mechanics in the past was to use AC discharged water, it's probably in the softened water range, and probably the best of both worlds.
 
I can add two bit of info that I got from real people, well before there was Internet...

- A mechanic I knew (we're talking 1978-79...) told me the best think to mix with antifreeze is... tea. Well he didn't mean it literally, he said it to highlight the point that if you simply take tap water and boil it then you get rid of much of the calcium.

- A friend who specialised in desiging water treatment and desalination plants (but knew very little about cars) told me never to use distilled water in metal or alloy cooling systems because it is highly corrosive. That was around 1985 I think.
 
I had the pleasure during the college phases of my apprenticeship to have a teacher old enough to have done winter/summer oil changes same applied to coolant, also I served my time in the best haulage dealership in the country, never once put coolant in an engine, drained new engines and it was straight water, we had a contract with castrol from oil all the way down to there wd40 equivalents, I maintain it’s all down to corrosion with cars, those who have will have witnessed corrosion when removing long in place cooling parts, plus with the possibility of three different metals sandwiched together there is the problem of one becoming an anode, that said I’ve seen trucks well past a million miles that saw nothing but straight water, cars are delicate little things in comparison
 
Interesting topic coolant complex like oil everyone has there own view.

From a personal choice when I get a new 2nd hand car as I have no idea what in it, I usually drain fully, refill with deionised water ( as I buy in 25 litres) run up to temp drain again and refill with makers approved ready mixed, run for month or so and drain and refill again with ready mix so im close to ratio, the last lot I got for this car with glow in dark lime green, so far works for me on my cars and to me I always feel better to know you have a single type of fluid in system and then change when you service car.

bit off from OPs post soz

Tezz
 
Interesting topic coolant complex like oil everyone has there own view.

From a personal choice when I get a new 2nd hand car as I have no idea what in it, I usually drain fully, refill with deionised water ( as I buy in 25 litres) run up to temp drain again and refill with makers approved ready mixed, run for month or so and drain and refill again with ready mix so im close to ratio, the last lot I got for this car with glow in dark lime green, so far works for me on my cars and to me I always feel better to know you have a single type of fluid in system and then change when you service car.

bit off from OPs post soz

Tezz

Premixed coolant obviously bypasses the entire issue, though it leaves us none the wiser....

Unlike engine oil, there's no secret formula, no mysterious additives, and no unverifiable marketing hype.

It's a simple matter, it's old school chemistry, with a yes or no answer. Yet everyone seems to have an opinion... how confusing.
 
If an engine was not able to survive with plain water frost plugs are pointless, well regarded engines even become pourous and hydro lock, they can even tell you how many hours till it happens,
 
Just to throw it in there, the most basic way of marinising an engine pumps salt water through system, lol, just put in whatever you got for the amount you lost and your good, unless your a purest, motorfactors don’t survive wrecking engines, I have a close relationship with one, oil is even a farce nowadays but that’s a different topic you’d be amazed especially us enthusiasts lol
 
Well.. my neighbour ..who is a mechanic.. did a diagnostic check with the scanner.. and no errors or codes showed up on that.. he has reset the whole system now to see if it comes back on again...
How is the engine light on without throwing a code, that’s what I’d be asking, cars complaining but it dosnt know what’s wrong!
Try this if you have spare coolant left, remove enough from bottle to trigger low warning, never heard of overfull warning, then you know that circuit it functioning, peace of mind, what class of scan tool did he use cause it’s a first to me there not being any code, did your friend explain that to you?
 
I had the pleasure during the college phases of my apprenticeship to have a teacher old enough to have done winter/summer oil changes same applied to coolant, also I served my time in the best haulage dealership in the country, never once put coolant in an engine, drained new engines and it was straight water, we had a contract with castrol from oil all the way down to there wd40 equivalents, I maintain it’s all down to corrosion with cars, those who have will have witnessed corrosion when removing long in place cooling parts, plus with the possibility of three different metals sandwiched together there is the problem of one becoming an anode, that said I’ve seen trucks well past a million miles that saw nothing but straight water, cars are delicate little things in comparison

how did that work in the winter?

I had an old rover V8 when I was very young and niaive and didn’t use anti-freeze - it didn’t end well for the motor.
 
how did that work in the winter?

I had an old rover V8 when I was very young and niaive and didn’t use anti-freeze - it didn’t end well for the motor.
If it froze there supposed to pop a freeze plug, trucks barely get a chance to cool down, if there idle you loose money, temps under a bonnet be a bit less harsh than around it, would have to sit there long time too, that was unlucky
 
If it froze there supposed to pop a freeze plug, trucks barely get a chance to cool down, if there idle you loose money, temps under a bonnet be a bit less harsh than around it, would have to sit there long time too, that was unlucky

fair enough. And as they say cars don’t like not being used 😉
 
I had MK 2 Cortina once and didnt put antifreeze in, it blew out a core plug one winter. Since then though I have checked anti freeze levels regulary, but never changed it on any car. I did change the coolant in my motorhome recently as this needed to be done after 2 years, research said most modern antifreeze types are miscible with G13 the latest standard to be mixed with de ionised water.
 
I had a 1979 Alfa Romeo that had proper coolant, and yet the head gasket blew, the head was seized on the block, and on removal (very complex process as they use studs, not head bolts) there were large pits in the alloy. Perhaps the Italian alloy was an extreme example, but water can be very corrosive, even when mixed with proper antifreeze. I then went on to make my own coolant using Ethylene Glycol, soft and distillerd water (perhaps not a smart choice), and corrosiion inhibitor pack. On my subsequent cars, I used Fiat Paraflu, which came ready-fix and was the gold standard for coolant among racers at the time. ... that was back in the eighties. Still not sure which is the best water to use... The last coolant change I did myself was 15 years ago on the Omega, I used genuine Vauxhaull/GM antifreeze mixed with tap water. When the thermostat was changed on my W204, Terry at Wayne Gates replaced the coolant. From memory he used genuine MB coolant, not sure what type of water he used. I decided to simply trust him and just let him do it how he always does it. He told me to double check the level the next morning, then add tap water, which I did, but it only needed a very small amount.
 
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I had the low coolant light come on when I was at my sons house in York which was 100 miles from home. A quick check on the internet showed the local water to be quite hard so I wasn't prepared to top up with that as the owners manual gives specific guidance on the water hardness limits. I nipped out to the local supermarket and bought some de-ionised water which the manual said was acceptable. Thankfully months later the coolant level doesn't seem to have dropped again.
 
I pour the coolant decide that’s enough, I grab the kettle pour till full, forget till I remember to check it, and will always. 😂
 
I always ensure the correct spec of engine oil and antifreeze when changing or topping up. As for the antifreeze, it’s g48 on mine and C3 Low saps oil.
 
I always ensure the correct spec of engine oil and antifreeze when changing or topping up. As for the antifreeze, it’s g48 on mine and C3 Low saps oil.

That's correct, though ideally you'll go by the specific MB Spec Sheet number for your car, rather than by the more-generic industry classification.
 
Just to throw my two bobs worth in this thread,we run two humidifiers in the summer and I use the water collected from them after SWMBO has grabbed what she wants for the steam iron, to top up the washer bottle,I always buy concentrate and I have never had a problem
 

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