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I may be wrong but... everyone recommends Shell Optimax and i believe it is of a higher octane. So i figured that super unleaded will have a higher octane as well and therefore better for the car.
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It varies from region to region, load to load, supermarkets just get it from whoever sells it them at the best rate.
A similar thing applies to other brands, they often are selling another brand's fuel, as their distribution facilities are nearer.
Brands are nothing but marketing tools. they sybolise little these days other than a "Buy me" signal for people who are taken in by adverts.
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Beaks
On the "Shell optimax in Pug 307" thread in Discussion, someone has contradicted my long-held understanding that RON numbers relate strongly to compression ratios. He may well be right and I await further views on that matter, but for now I'll stick to my position and say that the extra cost of Optimax is a waste of money unless your car has a high compression ratio and would therefore benefit from the 98 RON delivered by Optimax and no other fuel. It's not going to do any harm, but it won't be better for the car.
In saying this, I do assume that the additives in Optimax are comparable in quality with those in Shell's ordinary unleaded and, following HJ's lead, Texaco's too. It's the additives that make the difference and they do vary between brands. Apart from Optimax (guaranteed to be from Shell's own refineries), the base fuel can come from anywhere -- the fuel companies buy from one another frequently.
All that said, I do use Optimax.
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hi all,,,,all the supermarkets use petrol that has NO additives in..
where as ,,for example,,texaco have system clean3 and shell have there own version of cleaner already built in..
this is probably the only different...
also use 98 ron petrol in a higher performance car,,,an impreza for example,,should ONLY use 98 ron...optimax
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hi all,,,,all the supermarkets use petrol that has NO additives in..
Have you any proof of that claim? It has been suggested before by an ex tanker driver that all petrols have additives of one kind or another.
www.honestjohn.co.uk/forum/post/index.htm?v=e&t=67...5
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i once read it on the ferrari/ shell web site,,,,they were explaining why ferrari use a version of their optimax....and what the difference was,,,but it may take me a while to find it,,cause it was ages ago,,it was just a fact i remembered,,but i will go and look :)
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During my last year of commuting (mostly on motorways) I have logged amount of fuel required to fill tank to brim and mileage between fill-ups, hence calculated the MPG. I normally fill up at Safeway or Shell, and only after the tank is just less than 1/4 full. Car is a Focus 1.8 Petrol.
Safeway: 33.5 MPG
Shell: 35.3 MPG
Shell Optimax: 35.8 MPG
Safeway petrol seemed to offer the worse performance and increased engine noise. I didn't notice any performance advantage of Shell Optimax over normal Shell, but both seemed much better than Safeway. Best performance seemed to be with half Shell Optimax and half Safeway petrol. Seems that the price offers on Safeway petrol probably don't pay for the increased cost in fuel consumption...
Seasonal variations (slightly off topic) suggest the following:
Summer (no A/C): 37 MPG
Summer (A/C: 35 MPG
Winter: 33 MPG
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Outside air temp takes a big part in amount of fuel used.
--
Steve
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here you are dynamic dave
www.shelloptimax.co.uk/jive3/thread.jspa?forumID=1...0
try this link
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Storme, from your link:
"Yes they do, but they may not include performance enhancing additives such as detergents which are beneficial to the vehicle"
"May not" is different from "do not". Also, although I know nothing about the Shelloptimax website, common sense says that it will be doing everything in its power to try to convince you that its product is better, whether it is or is not?
As been said many times before, if one of these so called "premium fuels" was scientifically proved to be better then I am sure it would be advertised with these facts in a widespread campaign ie. with our fuel, you WILL get xmpg better than without, emissions will improve by x, and engine noise by y.
I have yet to see such an advert.
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Storme, from your link: "Yes they do, but they may not include performance enhancing additives such as detergents which are beneficial to the vehicle" "May not" is different from "do not". Also, although I know nothing about the Shelloptimax website, common sense says that it will be doing everything in its power to try to convince you that its product is better, whether it is or is not?
Detergents do not enhance performance, they reduce the propensity of gums in the petrol to stick to the various surfaces in the inlet path - chiefly the back of the inlet valve, injector components. All UK fuel has at least some detergent additive (to meet the revised BS EN 221 standard).
Performance and fuel mileage would only increase if more energy can be extracted from Optimax than from other brand fuels. This could be due to (1) higher calorific value (which is not the case) or (2) higher octane rating permitting greater ignition advance which may result in better thermal efficiency from the engine.
Cars that will benefit from Optimax are those that will benefit from higher octane rating of any brand fuel - typically 'performance' cars.
I note BP are now claiming 'better power and acceleration' from their fuel. Its about time these claims were tested - how about it, Consumers' Association?
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Aprilia
You said "how about it, Consumers' Association?" -- I've asked them twice. They have replied to say that it would be too costly to do properly. I suggested cooperation with their counterparts throughout Europe; they said they would consider it. If you and others with your technical cred were to write to them too at
editor@which.net
something might stir.
While I'm here, may I ask you to throw some authoritative light on octane rating in relation to compression ratios (see above)?
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"May not" is different from "do not".
Quite.
Also, although I know nothing about the Shelloptimax website, common sense says that it will be doing everything in its power to try to convince you that its product is better.
My sentiments exactly.
I'm not saying Shell are wrong in their *claim* but the link I provided was from someone who says he has delivered a variety of both branded and supermarket fuels.
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