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        General >> Off Topic Subjects >> Another Fuel Question
        
(Message started by: r33per on Sep 7^th, 2006, 8:18pm)

Title: Another Fuel Question
Post by r33per on Sep 7^th, 2006, 8:18pm

Recently, I've been hearing stories about other motorists having problems with the "Supermarket Grade" fuel. Some vary from a lower than normal MPG to serious performance lag and flushing out the fuel lines...

Has anyone here experienced any problems like this with the Scorpio?

Stu

Title: Re: Another Fuel Question
Post by TiberiuS on Sep 7^th, 2006, 8:48pm

Well, I filled my 2.3 up at Sainsbury's once when I ran low, it might have been me but the car didn't seem as responsive on the drive home. I normally fill up at Shell (yes, I even use Optimax when I feel flush, forgive me) and it suits me, normally a couple of coppers less than the BP down the road too.

One problem with cheap fuel is the sulphur content, google 'Nikasil' and you'll find a lot of information on the problems it causes with the Jaguar X308 XJ V8's and some Beemers, the sulphur content dissolves the cylinder lining, trashing the engine; one morning you start the car and get no compression...

The moral is, never buy a 'bargain' 1998 model Jaguar XJ with the original engine, you'll live to regret it as I nearly did (dreaming out of my price range :)).

Regards, TiberiuS ;).

Title: Re: Another Fuel Question
Post by Matt on Sep 8^th, 2006, 4:42pm

any one found a shell garage selling that v max stuff yet, the one near me still has optimax on the pumps :(

Title: Re: Another Fuel Question
Post by TiberiuS on Sep 8^th, 2006, 9:00pm

The two near me have Vmax on the pumps, pretty sure it's just a rebranded Optimax though ;)

Filled up tonight, 89.9p/litre; first time I remember it being below 90p for quite a while, won't last long though, the tank full or the price :-[

Regards, Bruce.

Title: Re: Another Fuel Question
Post by Matt on Sep 9^th, 2006, 5:35pm

almost vmax has a higher octane rating then optimax

matt

Title: Re: Another Fuel Question
Post by r33per on Sep 9^th, 2006, 9:26pm

on 09/09/06 at 17:35:31, Matt wrote:

vmax has a higher octane ...

Yeah, I was speaking to a guy at work about the octane thing. He said that it was to do with the height of the piston when it ignites the fuel.

Higher piston = better push on the downstroke = more power. However, because the piston is higher, it requires less fuel and so (theoretically...) the fuel economy should improve as well.

Is this correct, or have I missed something here?

Stu

Title: Re: Another Fuel Question
Post by TiberiuS on Sep 9^th, 2006, 9:53pm

I think he's right, the compression ratio has a bearing on output power, hence why cheap (low octane) fuel causes pinking and knocking.

The Scorpio handbook says that using higher octane fuel 'has no notable benefits'. I thought the main thing about Optimax was that it burned clean and contained additives to clean the engine. The higher octane can't be a bad thing though.

Whatever it is, the car seems to like it so I'm happy :)

Regards, Bruce.

Title: Re: Another Fuel Question
Post by taliban on Sep 9^th, 2006, 9:54pm

interesting, i thought the higher the octane the purer the petrol and therefore a cleaner more efficient burn.
isnt the height of the piston determined by the valves opening to let fuel into the chamber?

Title: Re: Another Fuel Question
Post by Matt on Sep 9^th, 2006, 10:12pm

the octane rating is something to with the fuel air mix, e.g. less fule is needed to produce the same power (cant remember the exact tech part right now, i'll find out again) normally, the octane rating has no effect on normal engines because it's not tuned to use the benefits (they wouldnt know it's a hight octane, so it prob just run rich), so any power increases experienced are from the additives being burnt. Car engines tuned for it, or high performance engines like the v6's would see some improvement, but as the newest cars are coming up to their 10th b'day, the technology is old and then we’re back to just burning additives :(

Title: Re: Another Fuel Question
Post by cossie_al on Sep 10^th, 2006, 11:46pm

I dont disagree with any of the above but one of the guys that goes to my local drives a fuel tanker and he reckons tankers from all the major companies fill up at the same place.
So when does the fuel change ie why is shell unleaded any better than sainsburys or tescos? ???

Title: Re: Another Fuel Question
Post by mr._floppy on Sep 10^th, 2006, 11:55pm

There are only a handful of petrol refineries in the UK and they're all run by the big companies Gulf, BP, Texaco ,Etc.

So the idea that Morrisons, Asda and Tesco have their own refineries is mistaken.

Title: Re: Another Fuel Question
Post by - Mike - on Sep 11^th, 2006, 12:02pm

on 09/07/06 at 20:48:49, TiberiuS wrote:

Well, I filled my 2.3 up at Sainsbury's once when I ran low, it might have been me but the car didn't seem as responsive on the drive home.

Funny you say that my sister put some petrol in her Vectra (only because we couldn't find a decent Scorpio at the time) from Sainsburys the other day and she commented that it ran like a bag of bolts afterwards. Normally theres no problem with the likes of Tesco's etc.

Title: Re: Another Fuel Question
Post by LiverpaulH on Sep 11^th, 2006, 1:35pm

Technically the base product is the same. Its what the company's add to the base product that makes the difference. Personally if I didn't run a diesel car (fuel from work - a haulage company) then I would use shell as a preference. We order our diesel for work from different suppliers (price can vary a penny a litre, which on 12,000 litres makes a difference!) and they pull from the same terminals, but the fuel is dealt with slightky differently by each of them.

A number of people I know have poorer running of their cars due to supermarket brand fuel. One person who really advises the use of branded fuel especially optimax is honest john of the telegraph newspaper (saturday motoring section) and his own website.

If I had a cossie then it'd be optimax only for me.

HTH
Paul

Title: Re: Another Fuel Question
Post by martin_rowe on Sep 12^th, 2006, 8:20am

octane value refers to the fuels resistance to detonation, higher octane has more calorific value, and burns slower, but longer.