Some petrol is better than others?

It was mentioned recently in this group, the opinion that branded petrol (ie shell, BP, esso etc) was better than the supermarket brands. To the extent that it could be detected in the better running of certain engines.

I would have thought that there were all sorts of trading standards coming into play here. Surely petrol cannot just end up without some sort of eye being kept on the quality and the Octane etc.

Would be interested to hear if others found some petrol was noticeably better than others? Thanks.

Reply to
john britain
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Yep, many years ago I found that my then current car (Montego 1600) ran better and did more miles to the gallon running on BP/Shell petrol that that supplied by the local supermarket[s].

Now, with the price of the stuff, I only use supermarket fuel (which now apparently has some of the common additives in it).

Reply to
Woodworm

Well I don't normally use supermarket petrol but did pop into Sainsbury's a few months ago after which my Rover kept refusing to accelerate. A taxi driver who gave me a lift to the garage which checked the engine over and found nothing wrong, suggested this was well-known amongst the drivers, though I have nothing to back it up.

I subsequently ran the tank down and have not been back since but used my regular Esso place down the road. It would be a huge coincidence if it wasn't fuel related in some way, but I agree that it's hard to understand how their fuel can be substandard. One suggestion, was that it might contain water but at the rate they turn it over, this sound infeasible to me.

Andy C

Reply to
Andy Cap

Well the Morrisons and Asda Tankers often can be seen filling up at Essos Purfleet depot so its probably the same stuff.

MattF

Reply to
MattF

Not necessarily, the additive package is added on the fly at loading time.

What's in the storage tank is blended hydrocarbons, and the additive pack, which is a minute percentage of the volume, is different for each brand.

For what it's worth, I used to own a diesel Citroen BX which ran better and used 10% less fuel when I filled it with Jet than when I used BP.

Reply to
John Williamson

It won't be water content. There is a standard for the octane rating, but the expensive stuff may be higher than the minimum, and may have more or better additives. Many cars have knock sensors and presumably the ECU tweaks all the settings. So they will probably advance the timing and improve the performance with a higher octane petrol.

Reply to
Newshound

You notice more of a difference with older engines (older designs I mean, not necessarily high mileage) and high performance engines. I've got a Mitsubishi FTO that's designed for the 100 RON fuel they have in Japan. It runs badly on regular unleaded so I use Shell V-Power, which at 98 RON is the closest available here. Owners of this car in other countries where 91 RON unleaded is available find that it won't even rev past 6200rpm (it redlines at 8000) as the knock sensor readings cause the ECU to limit the rpm to protect the engine.

Not all fuel is created equal. I've seen this topic come up on various forums (along with discussions on the merits of products like Redex) and you get the usual crowd who swear that it's all a marketing ploy just because their 0.9 Daewoo runs 'great' on Tesco's unleaded.

Reply to
Andrew
[...]

Conversely, my 1.6 Focus started to run roughly at tickover, especially when loaded up with a/c, and heavy electrical loads. It was so bad, it made the exhaust shake and rattle.

I couldn't find any reason for it; the only thing that had changed was that I had been trying a couple of tankfuls of the higher octane fuel, in an attempt to improve consumption. After a couple of tankfuls of regular, it was back to normal.

I can only guess that the higher octane fuel allowed the knock sensor to advance the ignition beyond a suitable value.

Chris

Reply to
Chris Whelan

That's interesting, as my Wife's Focus 1.8 petrol has suddenly started to hunt although very very slightly but only under load. The fuel in the car at the moment is from Sainsburys and I think it may be this fuel that's poor quality as the car was running perfectly until we put their fuel in.

I was thinking of putting some premium fuel in it to see if it stops but now think I'll just put standard fuel in from another petrol station.

Stephen.

Reply to
stephen.hull

My Mondeo 2.0 Duratec ran worse on Sainsburys Super Unleaded and generally isnt great on sainsburys fuel at all - i generally avoid it.

MattF

Reply to
MattF

[snip]

I topped up the Focus with another fuel today and the problem instantly went away, I'll not use sainsbury petrol again.

Stephen.

Reply to
stephen.hull

I often wonder if these issues are co-incidental, or a kind of placebo.

I can't say I've ever had dodgy fuel, both petrol and diesel, in all the hundreds of thousands of miles I've driven.

Reply to
Steve H

you have been lucky. The worst fuel I ever bought was many years ago, out in the sticks somewhere, I was towing a caravan. I filled up with Q8 petrol and within a few hundred yards of leaving the station the car started to pink really badly, even under the lightest accelleration. I had already travelled several hundred miles without problems, logically it was the fuel, I retarded the timing a little and the problem reduced dramatically, after the next fill up I was able to reset the timing to normal, so I am absolutely certain that the fuel was the fault.

Reply to
Mrcheerful

It's called "Confirmation Bias".

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We all do it :-)

Slatts

Reply to
Sla#s

Interesting, but certainly not the case where my car ran badly on higher octane fuel. I should have mentioned that when I was using that, I filled up with different brands, including Sainsbury's.

Chris

Reply to
Chris Whelan

Dad used to only use Esso, because it put a tiger in his tank.

Reply to
Gordon H

In message , Chris Whelan writes

I almost always use Sainsburys, because it is consistently one of the cheapest, and also contains Nectar additive.

Reply to
Gordon H

Or you just didn't notice it.

Reply to
Grimly Curmudgeon

There's not much point paying extra to avoid "dodgy fuel" if the difference is unnoticable!

Reply to
David Taylor

I have had people bring me cars for service with faults that I can hear from indoors, that they were unaware of, such as not running on one cylinder, exhaust falling off, loose wheel, brake pads on the metal, clutch slipping etc.. Some people are just not even slightly mechanically aware.

Reply to
Mrcheerful

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