Premium petrol/diesel - any difference?

[shotgun_tommy]

I recently put unleaded in my diesel . i put in 10 litres or so then topped with 50 litres diesel not by choice mind, anyhow the car didnt like it at all it would start then konk out smoke like hell sometimes then cut out while driving i persevered this way for about a week keeping topped up with diesel now the car runs fine no problem at all i think i am even getting more to the gallon than before.could this be right??

[aris]

I recently put unleaded in my diesel . i put in 10 litres or so then topped with 50 litres diesel not by choice mind, anyhow the car didnt like it at all it would start then konk out smoke like hell sometimes then cut out while driving i persevered this way for about a week keeping topped up with diesel now the car runs fine no problem at all i think i am even getting more to the gallon than before.could this be right??

 

I'm thinking the petrol cleared up your diesel injectors

 

I wonder if using 3 or 4 tankfulls of premium diesel would be a good idea just before your MOT - particularly in older cars.

Edited September 5, 2013 by aris

[TIGHTCHOKE]

 

Not sure why that assumption would be correct ? If for example you took a car and increased it's bhp by modifications then it would almost certainly give less economy !? Without meaningful tests you just don't know if you're getting better fuel consumption and for the record even if you did get marginally better results, superdooper stuff costs up to 10p more per litre in the first place !

 

It's basically called Badge Engineering in marketing terms, the whole retail scene is littered if you look carefully enough. Wines that are sold in fancy looking bottles can command higher prices compared to identical non frill bottom shelf stuff, guns are no different, you can buy a winner for a grand or be told £10k is where it's at, performance depends on the operator. Chocolate, clothes, watches, you name it.

 

Oh I nearly forgot cartridges, open up a game shell with fooiber and compare the insides with a club fooiber clay load, apart from one having 7.5 and the other having 6.5 shot size they'll be the same yet one will be dressed in gorgeous packaging with regular magazine adverts showing the squire ejecting a pair into the heather making you want it.

 

 

I think that sums up our CONsumer based world quite nicely!

[leeds chimp]

All about brand image really.....

has it actually been put to the test fully?

Might give it a go and see

[Will Poon]

I tried the more expensive shell diesel once , it made absolutely naff all difference to my car , the only thing I noticed was I was a couple of quid short in my wallet

Edited September 5, 2013 by Willpoon

[welsh1]

If i put normal unleaded in my st220 it hates it and pick up and overall performance is noticeably down it likes shell v max and seems to run very well on this.and i average about 25 miles more on a tank than against the normal shell fuel.

 

My navara has had all sorts put in it when i first got it but there is an advantage to using just shell fuel as i get about 20 miles more per tank than supermarket fuels,i will have to try there "super "diesel and see if the cost/mile extra ratio is worth it.

[brett1985]

I thought the simple answer when considering petrol was that the performance fuels contained anti 'pinking' agents to retard pre detonation of fuels in high compression ratio, performance engines?

 

you would be correct....

 

VAG group FSI and TFSI engines run ALOT better on premium fuel, with noticeably less pinking.

I have an 04 plate a3 1.6fsi, and if i use cheapo fuel it pinks like hell. with premium fuel it runs almost silent.

[shaun4860]

I drive a 2.2 litre deisel and use the cheapest fuel in the area, BUT every now and then, I put a bottle of engine cleaner in the tank and get somewhere in the region of 75 MPG.

Was it the trip computer telling you 75MPG or an actual brim it, run it, brim it test?

 

I find 75MPG in a 2,2 diesel a bit far fetched?

 

I had a renault 1.9 diesel where the trip was saying I was getting 93MPG at one point.....I wasnt of course

 

[superspark]

All fuels are refined to a certain standard which is carefully regulated. The only differance to the fuel will be the additives that different companies will add like carbon cleaners and the like. If you want to spend more of your money on fuel than you need to go right on ahead. Its your money or should I say its now theirs lol

[robbiep]

If people do test this, do bear in mind that the engine management software can take a few hundred miles to recognise that you have gone onto a 'premium' fuel, and adjust the mapping to suit. This used to be printed in the Subaru handbook, as they always recommended 98 RON fuels, due to the occasional lack of availability of such.

So, don't expect instant changes to your fuel economy as soon as you drive away. A tankful or even 2 may need to pass before it happens.

 

I do a lot of motorway miles. The 8-9% economy boost that I get is sitting with 75 on the clock with cruise control on. The additional BHP (assuming it is there) is allowing the car to run with less fuel for the same output. RPM is the same, as it is the same speed. But I've gone from 600-620 miles till the fuel warning to 680-700. A noticeable difference

[Chris Bb]

I've recently changed from Shell to BP, the garage is nearer & less crowded and the fuel is marginally cheaper.

 

MPG has definitely gone down.

 

Spurred on by this debate, yesterday I bit the bullet and filled up with Shell V Max diesel. So far I have driven 100 miles at my usual speeds over a variety of roads and the car's computer is showing a nearly 10% increase in MPG. I'll leave it ongoing for a few tanks full and will do the maths with actual miles and actual consumption before making a more realistic conclusion. But, at this early stage, I don't think I'll be going back to BP.

 

I'm still in two minds about whether it's worth doing the same for the Defender, however anything that reduces the black smoke on start-up is worth considering!

[aris]

It would be interesting to see if you got 10% over if regular Shell diesel rather than BP. Were you using premium BP?

 

Vpower diesel is an 8p premium over regular Shell diesel for me.

[figgy]

I wouldn't put any decent diesel in a defender any old cooking oil

or engine oil mixed with regular diesel. Black smoke soon clears when driving away, it don't look as bad in rear row mirror.

 

Figgy

[Chris Bb]

It would be interesting to see if you got 10% over if regular Shell diesel rather than BP. Were you using premium BP?

 

Vpower diesel is an 8p premium over regular Shell diesel for me.

 

OK, possibly not a fair comparison, I was using BP ordinary diesel but, as previously stated, it underperformed when compared with Shell ordinary. Just thought I'd give a modern high performance diesel engine a dose of "better" fuel to see the difference, if any.

 

8p premium @ £1.40 = approximately 6%, thus better than 5% increase in MPG is break-even or better.

 

Re the Defender, yup might try some cooking oil!

 

Edited to add value.

Edited September 12, 2013 by Chris Bb

[aris]

What car is it fister?

[welsh1]

Just a bit to add to this thread.

 

I decided the other week after a service to try running my navara on only shell v plus(premium) fuel.

Normally i fill from yellow light on and i get approx 450 miles showing on the trip meter that is reset each time.

 

Tank 1, saw no real difference in performance or mileage with trip meter showing 447

 

Tank 2, again no real difference to start, but toward the last 1/4 of a tank the engine sounded smoother and picked up slightly better,trip meter showed 456

 

Tank 3,engine is a lot quieter,still sounds like a diesel,but not like an old industrial diesel unit,pick up is a lot better and the trip meter showed 464

 

Tank 4,engine sounds sweet,pick up is very good and very smooth throughout the range,i drove this tank from pembroke to ormskirk and back, which involves going straight through the mountains,lots of up and down the box and varying speeds,i drove it like i stole it and was amazed that the trip showed 491.

 

So 4 tanks down and it seems that it has steadily improved the economy and performance.

 

the cost of the premium diesel has averaged £148.9 against normal diesel at £141.9 so it is costing approx £7.00 a tank more,at the moment i am going to try a few more tanks to see what it settles at and if it is worth continuing.

Edited September 22, 2013 by welsh1

[maxus77]

Cant believe no one has mentioned running on red, i seem to get loads further on that

[aris]

Welsh1 - what kind of fuel are you comparing it against? What were you using before?

[welsh1]

Welsh1 - what kind of fuel are you comparing it against? What were you using before?

I used shell and bp normal diesel before, and if stuck asda or tesco,the shell and bp were the ones that gave the 450 average tank run,the asda and tesco fuel used to fluctuate between 430-450,but the pick up was poor using them and a lot more black stuff out of the exhaust,also with the supermarket fuels the engine sounded like it was 30 years old.

 

The comparison would be against the normal shell,there is a definite improvement on pickup and performance,the engine sounds a lot smoother and the mpg is defiantly on the up,the question is will it cost me more in the long term to run the premium shell,if it is a £1 a tank difference then i think it would be worth it because it seems to be keeping the engine free from ****.

I do have my egr valve blocked off if that is of interest.

[aris]

At the moment it seems to be £7 for an extra 40 miles for you. A gallon of regular diesel is £6.45 at your prices (4.54l to the imperial gallon), so assuming you are getting 40-ish mpg, you are roughly breaking even on the money (back of the envelope calculation). But it sounds better, runs cleaner, more power, and presumably better for your engine. So overall, sounds like you are quids in.

 

Will be interesting to see how it looks in the medium term.

[welsh1]

At the moment it seems to be £7 for an extra 40 miles for you. A gallon of regular diesel is £6.45 at your prices (4.54l to the imperial gallon), so assuming you are getting 40-ish mpg, you are roughly breaking even on the money (back of the envelope calculation). But it sounds better, runs cleaner, more power, and presumably better for your engine. So overall, sounds like you are quids in.

 

Will be interesting to see how it looks in the medium term.

I get roughly the same figures,the problem is the fluctuating prices,can be 3p either way from day to day.

 

I agree that so far it all seems to be on the + side,i think i will run another 4 tanks and see if it has settled down to a consistent figure,would be nice if the 490 out of a tank is not a one off,will post up again after two tanks(one week) and again after the other two tanks.

[pimpkiller]

Tried having a go with a tank of the shell diesel v power nitro stuff after looking at this thread in interest and ive got to say the thing that struck me straight away was how smooth and more powerful the engine feels. My Fiat 1.3 multijet 90bhp (same as vauxhall 1.3 cdti) used to have real trouble pulling off in 1st and would judder like mad when slowing down in gear, but not anymore i assume thats because its a small poxy diesel and the higher RON suits.

 

On the economy front I cant reliably say since some of the old rubbish was still in and ive done a lot of short trips which is death to MPG but my gut instinct is to say that yes its better and ill keep on giving it a go.

[aris]

Welsh1 - if you do continue to get 490+ miles, try going back to regular diesel and see if it goes down. If not, or only after a tank or two, then perhaps the benefits can still be had by alternating between fuels.

[welsh1]

Welsh1 - if you do continue to get 490+ miles, try going back to regular diesel and see if it goes down. If not, or only after a tank or two, then perhaps the benefits can still be had by alternating between fuels.

I was thinking along the same lines,but wonder if the fuel management system would be put into a constant state of"turmoil"by the change of octane after every couple of tanks,as it seems to take a few tanks to adjust.

 

Any mechanics on here able to offer an opinion?

[aris]

As a follow-on to this - does anyone use any additives in their fuel? I have heard that Millers Diesel Power can give noticable improvements - similar to what people see with premium fuel (less smoke, more power/acceleration, better economy), at less cost. Just add 1ml per L of diesel at every fill-up. That roughly comes to about a pound per fill-up.