Winter diesel and Shell V Power

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Thu 12 Nov 2009 22:39
Winter diesel and Shell V Power - Ben79
I believe it is this time of year that winter diesel is being sold and a resulting loss of economy.

Would V Power diesel be likely to provide better economy during winter?

Thanks
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Thu 12 Nov 2009 23:22
Winter diesel and Shell V Power - idle_chatterer
Not sure of the impact of winter diesel but most of the consumer research (Motoring Which and What Car I think) leads me to the conclusion that the V Power diesel isn't worth the price premium.

It's a personal choice of course, however it just might be the case that any additional economy (and it's a moot point whether it actually gives any better mpg) isn't sufficient to cover the price premium.
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Fri 13 Nov 2009 08:25
Winter diesel and Shell V Power - aylesby
Ordinary winter diesel takes me from 51 to 48 in mpg
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Fri 13 Nov 2009 08:37
Winter diesel and Shell V Power - Peter D
IS that due to the deisel itself or the engine performace at a lower temperature. You would have to have a tank of winter deisel and nice warm day and along run to identify where the loss is. Regards Peter
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Fri 13 Nov 2009 08:44
Winter diesel and Shell V Power - Peter D
As you sure the mpg difference is not just the weather and nothing to do with winter deisel. You need a tank of winter deisel and a nice warm day and a long run to see if it stay down at 48mpg. Regards Peter
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Fri 13 Nov 2009 11:47
Winter diesel and Shell V Power - idle_chatterer
As an observation, my 330d is getting about 1.7mpg less at the moment (49.5 reduced to 47.8) whereas SWMBO's Civic it's more like 4mpg (47 reduced to 43, but it does a lot of shorter journeys). I'd never made the connection with winter diesel before !

Having Googled winter diesel I see it's all about additives to prevent waxing, I think the relative cost increase is more to do with demand for heating oil ?

What I have noticed is that my car gets better mpg on Shell 'normal' and Sainsbury's 'city' diesel, worst is BP and Morrisons, I'm not complaining, it's just an observation.

So back to the OP - I'd recommend Shell but wouldn't fork out for V Power.
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Fri 13 Nov 2009 12:50
Winter diesel and Shell V Power - ijws15
The Octavia returned the best MPG yet on the last tank!

It is sold to a BS whcih I believe includes a calorific value - should not be any different summer or winter.

May be more traffic on the cold dark nights, lights. fan/air con/ demister used more . . any numbr of things.
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Fri 13 Nov 2009 13:09
Winter diesel and Shell V Power - turbo11
Shell V power (unleaded) gave me around 3mpg improvement any time of the year in my Mazda 6. Now in my Mazda 5 I only get 1mpg difference. Same engine.
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Fri 13 Nov 2009 14:14
Winter diesel and Shell V Power - Andy P
No matter how I drive it or which grade of diesel I use, my 335d seems to stick at between 36.2 and 37.1 mpg. Not bad considering the lump under the bonnet.
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Sat 14 Nov 2009 20:21
Winter diesel and Shell V Power - Paddler Ed
At that MPG I struggle to see the appeal of a diesel... My GF can get nearly that out of my V70 classic with a petrol engine...
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Sat 14 Nov 2009 20:52
Winter diesel and Shell V Power - Old Navy
Is the V70 280 odd BHP and nearly 600 Nm?

Edited by Old Navy on 14/11/2009 at 20:55

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Sun 15 Nov 2009 06:51
Winter diesel and Shell V Power - oldtoffee
>>At that MPG I struggle to see the appeal of a diesel..

Maybe not for you but 0-60 in 5.7 seconds, 30-70 in 4.9, limited to 155mph and potential for over 30mpg would probably swing it for me ;-)
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Sun 15 Nov 2009 08:10
Winter diesel and Shell V Power - DP
I agree, the economy figures of Andy's 335d are not very impressive for a diesel, but hugely, incredibly impressive for a car with that kind of performance. How many 280 bhp, sub 6 second 0-60 auto-box cars can you think of that will do nearly 40 mpg? This is low 20's territory for a petrol engine.

This car has slightly better economy than my petrol Volvo S60, and more than half as much power again. There isn't a single head to head scenario where it wouldn't make my car look pedestrian. Diesel at its absolute best.

Edited by DP on 15/11/2009 at 08:13

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Sun 15 Nov 2009 08:26
Winter diesel and Shell V Power - cheddar
I have never noticed lower economy in winter.

Some years ago my old Vectra V6 did a couple of extra MPG on Shell Optimax (as it was then) so it paid for itself.

The Mondeo TDCi is also slightly more economical on V-Power or Ultimate diesel, it also feel a little crisper though that could be in my head. However it is clearly better for the CR pump etc.

I have tried a tankful of V-Power u/l in the FocuST, it didnt feel any different and was no more economical according to the computer, would need to be more scientific though.
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Sun 15 Nov 2009 09:17
Winter diesel and Shell V Power - b308
I never really noticed a difference with petrols in winter, C, but I've always seen a slight drop off in mpg with all the diesels I've had once the temperature drops, never put it down to the additives in the fuel, though.

I notice that on the odd days we have warm waether the mpg on the trip computer goes back up to summer levels so I'm not convinced the addatives have any negative effects.

Another vote for "ordinary" Shell, though, I've tried the v power stuff and not seen any real difference, certainly nowhere near justifying the extra price!
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Sun 15 Nov 2009 10:58
Winter diesel and Shell V Power - dieseldogg
Well with the Galaxy TDI on 20,000 plus miles on the origional injectors
(The pump was unfortunately changed needlessly at 50thou, but thats another storey)
run on a mixed bag of forecourt diesel
winter figs about 2.5mpg behind summer figs ( in the middle high forties usually)
colder therefore slower to warm up to optimum op temp
I CANNOT see that the premium price for better diesel could ever recoup itself
in the fractional extra MPG gain

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Sun 15 Nov 2009 13:49
Winter diesel and Shell V Power - Falkirk Bairn
Ultimate & Vpower diesel gives me no mpg advantage.

The car runs more smoothly and there is never the sooty wake when I give it a few extra revs for overtaking etc.

My 11 yr old petrol Mazda gets through MoT emissions with no problems. A pound or 2 a week in petrol makes less potential problems come October MoT time.
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Mon 16 Nov 2009 23:05
Winter diesel and Shell V Power - cheddar
I agree the economy figures of Andy's 335d are not very impressive for a diesel
but hugely incredibly impressive for a car with that kind of performance. How many 280 bhp sub 6 second 0-60 auto-box cars can you think of that will do nearly
40 mpg? This is low 20's territory for a petrol engine.


Thinking about this today, the 330d is even more impressive, performance in the same realm as the 335d and nearer 50 mpg than 40.
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Mon 16 Nov 2009 23:51
Winter diesel and Shell V Power - idle_chatterer
I easily get 45 to 50 mpg out of my 2009 330d touring manual, it has a claimed 0-62 time of 6.2s, - that's a mere 0.1s slower than the auto 335d. In gear it is supposed to rival a Boxter S too (I think).

If I'd gone for an auto the 335d would have been high on my list, but again I think the 330d Touring auto dispenses 0-62 in a claimed 6.3s and delivers mid 40s mpg with a little careful driving. CO2 (rather than lease cost) put me off the 335d due to BIK tax.

I wonder when the updated 3.0 lump from the 330d / 730d will get the 335d twin turbo treatment ? That might be some motor....

And to keep on topic - I never (ever) pay extra for V-Power or Ultimate or suchlike.

Edited by idle_chatterer on 16/11/2009 at 23:53

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Tue 17 Nov 2009 10:59
Winter diesel and Shell V Power - concrete
I have run diesels for years and i am a huge fan. I have never found the extra for premium fuels worth it. I have found that some supermarket fuels(not all) give poor performance and general running. I now just stick to Shell or BP ordinary diesel and return never less than 49mpg in mixed driving. Not bad for 130bhp turbo in a big car. Summer or winter there seems to be no difference to me in performance or consumption. Most of my journeys are fairly long though and on good roads. Concrete
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Tue 17 Nov 2009 11:49
Winter diesel and Shell V Power - madf
Like concrete I see zero difference from premium fuels. I use only Shell or BP ordinary diesel and have done so since our first diesel in 1993. Never had any problems with anything sticking. 75% of journeys under 7 miles.

Winter mpg always falls off a bit: cold oil and water I assume and on very cold days, very cold gearboxes...
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Tue 17 Nov 2009 12:35
Winter diesel and Shell V Power - dieselfitter
Agree with Concrete - some supermarket diesels would cause my Mondeo III TDCi to run badly, almost like a misfire. I can't detect any difference in mpg with the premium diesels either, but I tend to use them now in my new A6 in a vague and uncertain belief that they burn cleaner, are less likely to form deposits on injectors, maybe less soot for the DPF to absorb. We need a fuel expert to tell us whether this is likely to be true or not. I did know such an expert (sadly no longer with us). He reckoned that the premium diesels (V-Power, Ultimate, Excellium) are produced by gas to liquid (GTL) technology, not by distillation of crude oil. As such they are significantly cleaner. Does this mean they are better for a state-of-the-art diesel engine, assuming it's your money and you aim to keep the car long-term??
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Tue 17 Nov 2009 23:00
Winter diesel and Shell V Power - Dave_TD
I posted my findings at the time, but it basically depends on the individual car.

My Octavia SDi (slightly different league to your 335ds or even Mondeo III TDCis admittedly) gave 45mpg on normal diesel and 51mpg on BP Ultimate, so I ran it on Ultimate for almost 200,000 miles. Better performance than the other SDis in the fleet to boot.

My 406 2.0HDi 90 gave 36mpg on normal and also 36mpg on Ultimate so after a few trial tankfuls I stuck with the cheapest. Performance was never as good as the 68PS Octavias...

My Escort 1.8 16v 115PS ('97R, 102k miles) gives between 36-42mpg on normal unleaded and between 40-43mpg on Shell VPower, so it gets VPower when I'm passing the Shell garage but I don't make a special trip for it.
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Sat 12 Jan 2013 15:33
Winter diesel and Shell V Power - mss1tw

Anecodotal, but as it's easy to run a Berlingo flat out without going near licence losing speeds, I can confidently say that on winter diesel it struggles to pull more than 85mph.

In the summer it would sit at 90mph on the flat easily enough. Would only do that downhill today. :-D

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Sat 12 Jan 2013 16:32
Winter diesel and Shell V Power - unthrottled

In the summer it would sit at 90mph on the flat easily enough. Would only do that downhill today. :-D

That's because air density increases as the temperature falls. That increases the drag. Nowt to do with the fuel!

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Sat 12 Jan 2013 16:59
Winter diesel and Shell V Power - RT

You also need to take into account air pressure which generally drops in winter thus reducing the drag - but you also need to take the moisture content into account as high humidity will increase the drag.

It ain't simple !

Winter diesel is a different formulation that flows better at low temperatures and has a slightly lower calorific value - which accounts for the loss in performance and economy.

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Sat 12 Jan 2013 17:06
Winter diesel and Shell V Power - mss1tw

I thought cold air overall helped performance as it is denser meaning more oxygen?

Also when I used to do motocross, the (2 stroke) engines would only tick over on damp days. It was turned right the way down just in case of an accident. On 'normal' days constant blipping was required. To me this indicated the engines preferred moist air.

What you say still makes perfect sense though.

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Sat 12 Jan 2013 17:31
Winter diesel and Shell V Power - Collos25

www.kfz-tech.de/Engl/Dieselkraftstoff.htm

Good site if you want the facts and figures.

Calorific values Winter diesel 36-38MJ per KG

Summer diesel 44-45 MJ per KG

Edited by Collos25 on 12/01/2013 at 17:38

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Sat 12 Jan 2013 17:34
Winter diesel and Shell V Power - RT

I thought cold air overall helped performance as it is denser meaning more oxygen?

Also when I used to do motocross, the (2 stroke) engines would only tick over on damp days. It was turned right the way down just in case of an accident. On 'normal' days constant blipping was required. To me this indicated the engines preferred moist air.

What you say still makes perfect sense though.

Cold air doesn't help a diesel with turbocharger and intercooler - diesels run with excess air/oxygen anyway so a slight increase doesn't help.

High humidity messes up the fuelling on a petrol engine, but in a good way, as the water content contains oxygen - I guess it's like water injection but at much lower effect.

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Sat 12 Jan 2013 17:43
Winter diesel and Shell V Power - unthrottled

but in a good way, as the water content contains oxygen

But the oxygen is already combined with hydrogen so it isn't available for combustion! Humidity is useful for improving detonation resistance though.

So when someone says that their car is running so muchbetter on 97 RON when it is cold and damp outside, you know the placebo affect is at work... :)

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Sat 12 Jan 2013 17:40
Winter diesel and Shell V Power - unthrottled

I thought cold air overall helped performance as it is denser meaning more oxygen?

It does. But you need more power to overcome air resistance, so your top speed will fall slightly.

Also when I used to do motocross, the (2 stroke) engines would only tick over on damp days.

Apples and oranges. Air cooled enginnes' (or liquid cooled bikes with tiny radiators) operating temperature is directly affected by ambient conditions. Since the intake air is drawn through the crankcase, the metal temperature makes a big difference to the density of the charge for a given throttle opening. Car engines are affected to a much smaller degree.

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Sun 13 Jan 2013 13:05
Winter diesel and Shell V Power - madf

nges. Air cooled enginnes' (or liquid cooled bikes with tiny radiators) operating temperature is directly affected by ambient conditions. Since the intake air is drawn through the crankcase, the metal temperature makes a big difference to the density of the charge for a given throttle opening. Car engines are affected to a much smaller degree.

Err normally aspirated one maybe..

Turbo charged ones need an intercooler which works better at low ambients...

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Sun 13 Jan 2013 14:17
Winter diesel and Shell V Power - unthrottled

Absolutely true-when the turbo is under significant boost-which isn't all the time.

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Sun 13 Jan 2013 17:31
Winter diesel and Shell V Power - valvebounce

I believe winter diesel has additives which lower the octane levels to prevent it starting to thicken up or freeze. Lower octane means less mpg.

I think V power has a higher octane level,but unless your ecu can automaticaaly re-map,you are just blowing it through with no advantage in mpg.

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Sun 13 Jan 2013 18:57
Winter diesel and Shell V Power - unthrottled

I believe winter diesel has additives which lower the octane

Octane and diesel?!

The composition of winter diesel is slightly different to prevent it waxing at low temperatures). It's slightly less dense (lighter chains) so the calorific value is less. But the difference is small, comparable to adding 5% biodiesel to petrodiesel. No one noticed a fuel economy drop when 5% bio became mandatory, did they?!

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Sun 13 Jan 2013 21:00
Winter diesel and Shell V Power - MikeTorque

I did.

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Mon 14 Jan 2013 01:47
Winter diesel and Shell V Power - valvebounce

I wasnt conversant with the equivilent term for the octane of deisel,I can see now they call it calorific value.Either way,it is the speed and explosive power of combustion of course.

I converse on an American outboard motor blog,they use aircraft petrol of 120 octane in some of their powerboats,and tune them to suit the higher octane.

Apparently aircraft fuel has little or no ethanol in it for safety reasons.i.e.melting seals and gaskets.

Years ago."National petrol stations" used to sell 101 octane petrol,it was a favorite with bikers,who had their engines tuned to suit.

The lower the octane or calorific value,the slower and lesser the explosion in the engine cylinder,which leads to less mpg.slower engine pickup and power.

There is a small ethanol percentage added to all uk petrol.Vintage vehicles are vulnerable to seals and gaskets melting due to the ethanol,because the materials they were made from are not modern spec.materials.

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Mon 14 Jan 2013 15:20
Winter diesel and Shell V Power - galileo

For information, cetane number is the rating for diesel fuel which is analogous to octane rating for petrol; it is (roughly) a measure of how easily the fuel ignites under compression, so exactly opposite characteristics to octane number.

Neither rating is directly related to calorific value

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Mon 14 Jan 2013 16:13
Winter diesel and Shell V Power - RT

Neither rating is directly related to calorific value

No but .....at the levels used in cars, 95-101 RON, the octane number is roughly linear to the usable energy IF the engine automatically adjusts it's ignition/injection mapping to optimise the fuel available.

Diesel is more complicated.

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