Which Petrol to use? Advice please

Robisere

It makes no difference to the average motor whether you fill up at a "Branded" pump or not. It all comes from the same holes in the earth or seabed and it all goes to the same refineries, with the same standards.

I use a little from a "Branded" pump some of the time, then every 3 weeks or so I drive to my nearest big supermarket (Morrison's) 22 miles away and do a big shop, then fill my tank to the brim. The worst thing any driver can do, is to allow the tank to become almost empty, especially with an engine that has been subjected to a high mileage. There is a fine "sludge" formed at the bottom of all fuel tanks over a long period and this can be drawn into the fuel/air mix, with consequent problems. Keep it topped-up!

To the anti-supermarket protestor - families cannot afford to ignore supermarket prices, even if you can. And I use Morrison's because they stock fresh, mostly British, food. I have never noticed any difference between Supermarket fuel and any other, except that the Morrison's stuff is less expensive and gives me points towards my shop.

pedrothefish

Many thanks for all the replies it certainly makes interesting reading.
My conclusion is carry on with supermarket fuels and if shell or bp match it then fill up.
Someone mentioned giving it some revs in third occasionally, I do this now and again, getting up to about 5000 revs in 3rd then 4th once the engine is hot. Is this ok?

alastairq

Someone mentioned giving it some revs in third occasionally, I do this now and again, getting up to about 5000 revs in 3rd then 4th once the engine is hot. Is this ok?

That would be me then?

ANd...no, I advise not to rev so high , whilst the engine is cold.

No bother, though, once the temp gauge is up and steady.

And, if you're doing 5000 revs in third, why bother with 4th?

Just go straight into top gear [from the above 3rd], relax and croooze?

oscarward

Some years ago (28 to be precise) I 'inherited' a car from a relative who couldn't afford to run it.

I subsequently discovered he had !!!!!! the ignition to run on cheapest 2 star rather than 3 or 4 star petrol.

The engine fell apart about 3 months later. The pistons had been burnt which led to combustion products getting in to the crankcase and contaminating the oil which scrapped the cam shaft and crankshaft.

I now run a high performance diesel engine car. I've recently tried using Shell ordinary diesel rather than my usual Asda/Morrisons and have seen the trip computer reading go from 36ish to 39ish mpg. Gone back to using supermarket and the mpg dropped.

So now I try and use Shell when I can but only if they are price matching (ish).

Ultrasonic

oscarward wrote: »

I now run a high performance diesel engine car. I've recently tried using Shell ordinary diesel rather than my usual Asda/Morrisons and have seen the trip computer reading go from 36ish to 39ish mpg. Gone back to using supermarket and the mpg dropped.

So now I try and use Shell when I can but only if they are price matching (ish).

If you really see that improvement in mpg with Shell fuel (just over 8%) then you should always buy Shell fuel unless it is more than 8% more expensive (which it won't be, as that's more than 10p extra per litre). Although you may want to be a little more scientific about seeing if that really is a genuine increase of 8%. I'm skeptical, there are so many other factors that could have caused you to see what you did.

GolfBravo

oscarward wrote: »

I now run a high performance diesel engine car. I've recently tried using Shell ordinary diesel rather than my usual Asda/Morrisons and have seen the trip computer reading go from 36ish to 39ish mpg. Gone back to using supermarket and the mpg dropped.

The trip "computer" is not a scientific measuring device, and the industry standard margin of error is 10%. It doesn't know how much fuel is being used, it just estimates it - the car can't measure how much fuel passes through the fuel rail, so it uses the MAF sensor readings, and then calculates the estimated fuel usage based on how high the air fuel ratio is vs how much air passes through the MAF. The other method is to measure the fuel line pressure and the injector open time window.

Both methods are not scientific, and even a simple air temperature difference can affect the measurement.

The only accurate MPG measurement is a brim to brim calculation.

oscarward

GolfBravo wrote: »

The trip "computer" is not a scientific measuring device, and the industry standard margin of error is 10%.

The only accurate MPG measurement is a brim to brim calculation.

When I've done that the calculated actual mpg, about 3 or 4 times when I can remember, it usually agrees with the trip mpg to within 1 mpg. Which did surprise me.

As I said I try and use a branded fuel when it is within a pence or 2 of supermarket prices. Life's too short to worry otherwise.

artbaron

fivetide wrote: »

That's not strictly true.

Subaru for example say 98 is the best as the cars in Japan run on 100 RON. However, they will happily take 95.

I know two people who blew their Subaru engines because they used 95 RON. The first guy is a Subaru mechanic and blew the engine on the track after chancing it with 95 fuel for the first time. The other bloke was my neighbour and after two tanks of 95 RON his new £40K WRX gave up the ghost and left him with a 5 figure repair bill which was eventually paid on warranty but not before arguments over him using incorrect fuel.

Weird_Nev

Anyone running a Subaru on track on cheap fuel deserves to buy a new engine.

And if it was a £40k WRX then it must have been a very, very special edition. I can only think of a couple of limited run cars that hit that price. As such it was most likely a very highly tuned STi and would ahve specified 98 RON minimum. Mine was only a WRX with a Prodrive map and even that came with dire warnings about only using 98 RON fuel.
Either that or it was more like a £25k WRX.

Strider590

Robisere wrote: »

To the anti-supermarket protestor - families cannot afford to ignore supermarket prices, even if you can. And I use Morrison's because they stock fresh, mostly British, food. I have never noticed any difference between Supermarket fuel and any other, except that the Morrison's stuff is less expensive and gives me points towards my shop.

Or you could do what I do, which is get a trolley full of shopping at Aldi or Lidl for £60 (as opposed to £150 in Morrisons) and then buy branded fuel at 2p a litre more, but also not care because I don't have to go further than the next street to get it.

I know i'm lucky in a way because my Aldi is next to a Morrisons, so I buy the basics there and then hop over to Morrisons for the "posh" stuff, which used to include bread at £1.30 a loaf, but Aldi now do a better one for 89p.

Seriously though, with the extortionate food prices in the big supermarkets, your not saving anything by using their fuel.

As for points...... They make up for that with overpricing, the store cards are little more that a marketing tool. We worry about online privacy, but via store cards the supermarkets know more about you than any hacker could ever know.
Got kids? they know that and they know how old they are (because you were buying nappies 4 and 6 years ago).