RE: What is AdBlue? PH Explains

RE: What is AdBlue? PH Explains

Author
Discussion

LotusOmega375D

7,641 posts

154 months

Wednesday 21st November 2018
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^ thanks, just ordered.

apm142001

276 posts

90 months

Wednesday 21st November 2018
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By all accounts, dealers keep VERY quiet about the AdBlue requirement when buying a new car.

A mate (who's definitely not of a Pistonheads persuasion) bought an F-Pace last year and was taken rather by surprise when a message about low AdBlue popped up (he, of course, had no idea what the stuff was either).

As for consumption, the new Duster (for example) supposedly needs a tank of AdBlue for every 6 tanks of fuel, which sounds like a bit of a bore..though would agree with the article in that cleaner air is worth the hassle, on balance.

tekyd

18 posts

151 months

Wednesday 21st November 2018
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So the requirement in the system is really for Ammonia? The breakdown the 'AdBlue' creating that and Carbon Dioxide...you know the other key greenhouse gas which I presume joins the existing CO2 output from the engines fuel burn and out in to the wide world...

So is CO2 the lesser of two evils here?

IknowJoseph

542 posts

141 months

Wednesday 21st November 2018
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WonkeyDonkey said:
I do a lot of motorway journeys at 60mph so guess it's not used as much as if I was doing a lot of town driving or fast motorway driving.
Or even appropriate speed motorway driving winkbiggrin

otolith

56,212 posts

205 months

Wednesday 21st November 2018
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tekyd said:
So the requirement in the system is really for Ammonia? The breakdown the 'AdBlue' creating that and Carbon Dioxide...you know the other key greenhouse gas which I presume joins the existing CO2 output from the engines fuel burn and out in to the wide world...

So is CO2 the lesser of two evils here?
At 32.5% CH4N2O by mass, with the molecular mass of urea being 60.06, one mole of urea being oxidised to one mole of CO2, the molecular mass of CO2 being 44.01 and with a litre of AdBlue weighing about 1.1kg, I make the CO2 emissions from a litre of AdBlue;

(1.1kg * 0.325) / (60.06 g/mol) * (44.01g/mol) = 262g of CO2.

Burning one litre of diesel releases ~ 2680g of CO2.

So the direct CO2 release from using a litre of AdBlue is about the same as that from burning a tenth of a litre of extra diesel.

If the car uses 1.5%-5% of the diesel consumption in AdBlue then the additional CO2 output will be about a tenth of that - 0.15% to 0.5% more CO2 in return for not having to breathe NOx sounds tolerable.

tekyd

18 posts

151 months

Wednesday 21st November 2018
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otolith said:
tekyd said:
So the requirement in the system is really for Ammonia? The breakdown the 'AdBlue' creating that and Carbon Dioxide...you know the other key greenhouse gas which I presume joins the existing CO2 output from the engines fuel burn and out in to the wide world...

So is CO2 the lesser of two evils here?
At 32.5% CH4N2O by mass, with the molecular mass of urea being 60.06, one mole of urea being oxidised to one mole of CO2, the molecular mass of CO2 being 44.01 and with a litre of AdBlue weighing about 1.1kg, I make the CO2 emissions from a litre of AdBlue;

(1.1kg * 0.325) / (60.06 g/mol) * (44.01g/mol) = 262g of CO2.

Burning one litre of diesel releases ~ 2680g of CO2.

So the direct CO2 release from using a litre of AdBlue is about the same as that from burning a tenth of a litre of extra diesel.

If the car uses 1.5%-5% of the diesel consumption in AdBlue then the additional CO2 output will be about a tenth of that - 0.15% to 0.5% more CO2 in return for not having to breathe NOx sounds tolerable.
Now that's my kind of answer! :-)


otolith

56,212 posts

205 months

Wednesday 21st November 2018
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thumbup

Sheepshanks

32,807 posts

120 months

Wednesday 21st November 2018
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WonkeyDonkey said:
Picked up 7 litres from asda for a fiver the other day.

Had my cactus for 14,000 miles now and not had to top it up yet so thought it must be due soon.

I do a lot of motorway journeys at 60mph so guess it's not used as much as if I was doing a lot of town driving or fast motorway driving.
Bit of Googling says it's a 17litre tank in Cactus, which is on the large size (wife's Tiguan is 12 litres). AdBlue is used in ratio to fuel used so your economical driving is helping but to not even have seen the 1500 mile warning by 14K is pretty good going.

A900ss

3,253 posts

153 months

Wednesday 21st November 2018
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My previous Merc C220d had a big enough tank to go the full distance between services without a top up (just over 15k miles).

My new Passat has a much smaller tank and can only manage about 8k before I need to fill up.

As others have stated, I can’t be bothered with buying containers and using funnels/adaptors. I just fill up at Truck stops. Moto seem good, you just need to leave a pre-payment deposit. The truckers seem OK with you using their pumps as well as you are only there for a couple of minutes.

https://www.volkswagen.co.uk/technology/diesel/adb...

Edited by A900ss on Wednesday 21st November 15:09

Sheepshanks

32,807 posts

120 months

Wednesday 21st November 2018
quotequote all
apm142001 said:
By all accounts, dealers keep VERY quiet about the AdBlue requirement when buying a new car.

A mate (who's definitely not of a Pistonheads persuasion) bought an F-Pace last year and was taken rather by surprise when a message about low AdBlue popped up (he, of course, had no idea what the stuff was either).

As for consumption, the new Duster (for example) supposedly needs a tank of AdBlue for every 6 tanks of fuel, which sounds like a bit of a bore..though would agree with the article in that cleaner air is worth the hassle, on balance.
I'd be amazed if any salesman volunteered the information.

Wife got one the first Tiguans to have it in Sept15 - I was aware of it and discussed it with the salesman who knew about it. He just referred to VW info online - but that was changing every time we looked. Certainly it was being said at first that "it's a service item" and the car wouldn't need to topped up by the owner. However it soon became clear that there's no way that's correct on VAG cars. Apparently except on Audis sold in the US where they disabled AdBlue during highway cruising!

On that model Tiguan (last of the mk1's) it's a right faff as the filler is under the boot floor and the spare wheel has to come out so it's a 15-20 min job to fill and not something you'd want to do in a service station. There were reports of VW taking cars back off high mileage users who hadn't been told about it.

B17NNS

18,506 posts

248 months

Wednesday 21st November 2018
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Came her looking to find out what AdBlue is.

PH you have done me a disappoint.

A900ss

3,253 posts

153 months

Wednesday 21st November 2018
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B17NNS said:
Came her looking to find out what AdBlue is.

PH you have done me a disappoint.
They are just taking the piss

Mr Pointy

11,246 posts

160 months

Wednesday 21st November 2018
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What would happen if you didn't use Adblue but just added deionised water? Would it muller the catalyst or would the engine systems detect it & refuse to start the engine?

WonkeyDonkey

2,341 posts

104 months

Wednesday 21st November 2018
quotequote all
Sheepshanks said:
Bit of Googling says it's a 17litre tank in Cactus, which is on the large size (wife's Tiguan is 12 litres). AdBlue is used in ratio to fuel used so your economical driving is helping but to not even have seen the 1500 mile warning by 14K is pretty good going.
I'm guessing the light will come on in the car tonight now I've said that!

Just saw it on the reduced to clear rack so thought it'd be handy to have incase I do suddenly need it! Didn't realise my tank was that big though.

MG CHRIS

9,086 posts

168 months

Wednesday 21st November 2018
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As another poster mentioned don't fill them too the brim Peugeot who I work on welltry and avoid anyway are having bid issues with pressure sensor faults in the ad blue tank, when removed the plug and sensor is full of crystalised ad blue that has been forced into it when the tank expands. The early cars didn't have a vent in the cap but there is a recall for a improved cap with a vent however it isn't really improving things that much.

freeform

53 posts

161 months

Thursday 22nd November 2018
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Mr Pointy said:
What would happen if you didn't use Adblue but just added deionised water? Would it muller the catalyst or would the engine systems detect it & refuse to start the engine?
The cat won't mind but it's a closed loop system; the NOx sensor will detect tailpipe NOx and the system controller will realise the implausibility of poor convervion vs the amount of AdBlue it thought was being dosed. That is sufficient to meet EOBD regulation, at present. In other markets - the USA - a quality sensor may be needed in the tank to pick up this mis-filling more quickly.

LotusOmega375D

7,641 posts

154 months

Thursday 22nd November 2018
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GranCab said:
Euro Car Parts £7.99 for 10 litres

https://www.eurocarparts.com/ecp/p/car-accessories...
Ordered this yesterday and received it today by DHL. So that's 10 litres delivered to my door next day for £7.99, compared to those first 3.5 litres picked up from my local ASDA filling station for £7.00. At least my average price per litre of £1.11 isn't as bad as the £2.00 it was.

Anyway it's all in the car now, so I won't have to think about it for another year.

A900ss

3,253 posts

153 months

Thursday 22nd November 2018
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LotusOmega375D said:
Anyway it's all in the car now, so I won't have to think about it for another year.
10 litres to last a year? That’s very good going. How many miles will that last?

I fill the tank every 3 to 4 months.

Edited by A900ss on Thursday 22 November 16:49

LotusOmega375D

7,641 posts

154 months

Thursday 22nd November 2018
quotequote all
I only did 6600 miles in that first year and it said it had enough left for another 1400 miles or so. I don't how much Adblue it came with from the factory though (new Passat).

A900ss

3,253 posts

153 months

Thursday 22nd November 2018
quotequote all
LotusOmega375D said:
I only did 6600 miles in that first year and it said it had enough left for another 1400 miles or so. I don't how much Adblue it came with from the factory though (new Passat).
Ah, same car then!!! I’ve got a 2.0 TDI DSG. Small tank though and I do 30-35k a year.

I reckon mine came with a 70/80% fill when I picked it up new in June. I put in 9.5 litres at 5,300 miles as I was about to go on a family holiday to the Alps and wanted to ensure I didn’t need to top up over there.