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Shell Optimax: The wonder fuels that don’t deliver


The Sunday Times: The wonder fuels that don’t deliver

“In February this year the Advertising Standards Authority upheld complaints against the claims Shell was making in its adverts, including that Optimax gives “an extra burst of power just when you need it”.

By Dave Pollard of The Sunday Times

October 03, 2004

The ads claim they are wonder fuels but our test was less than impressive

It is, according to Shell, petrol “with a dash of Ferrari”. Or as BP prefers to put it, fuel with “extra oomph”. Both oil giants are piling massive marketing budgets into their premium fuels — Shell’s Optimax and BP’s Ultimate. The fuels are on sale at the same pumps as ordinary unleaded, but cost about 20p per gallon more. The companies are keen to convince you to pay.

“Spinach did wonders for Popeye,” says BP’s latest magazine advert, “BP Ultimate will give your car a similar boost. Perkier performance, sharper response, smoother acceleration.” Another claims the fuel “can make a 1.8 litre vehicle perform like a 2 litre”. The BP website reinforces this with pictures of cars running on Ultimate zooming past those using conventional unleaded.

Shell’s Optimax adverts are heavily circulated on television and radio, with a voiceover by the motoring journalist Quentin Willson. Its website offers similarly enticing promises: “All unleaded vehicles can benefit from using Shell Optimax” and “Optimax can begin to improve your vehicle’s responsiveness from the moment you use it”.

Yet elsewhere on Shell’s own website, the gloss begins to come off this apparent wonder fuel. Shell has included an internet message board, but rather than extolling the virtues of its product many of the messages take a different tone: “I have tried Shell Optimax on several occasions (whole tankful) and have not noticed any difference at all,” says one message. “I think this is just another way to get more money out of the gullible motorist.”

So do they make a difference? To put them to the test we enlisted the services of Superchips, based in Buckingham, which has been a leading engine tuning company since 1989. It carries out tuning work for several car manufacturers and racing teams but has no links with oil companies. Ford provided a Focus C-Max which we mounted on the rolling road in the Superchips laboratory. Computers attached to the engine measured the power (in brake horsepower) and torque as we ran the car, first on a gallon of standard unleaded, then on Optimax and Ultimate respectively.

The results surprised us all. The torque and power graphs produced for all three fuels as the car accelerated from low through to high engine revs were virtually identical. Maximum torque was the same for the three fuels, and horsepower was almost equal throughout the acceleration range, except at very maximum revs where Optimax and Ultimate managed just one extra bhp. But even this 1bhp is not significant because at other points in the rev range the standard unleaded petrol gave marginally more horsepower anyway.

“Looking at them cold, any automotive engineer would simply assume they were three runs using the same fuel in the same engine, with no alterations to anything,” said Ian Sandford, the managing director of Superchips. “There’s certainly nothing here to suggest that using either super fuel would give a noticeable difference in performance.”

The basic reasoning as to why the super fuels boost performance is that they have a higher octane rating (they are more explosive). Normal unleaded is 95RON (research octane number), while Optimax is 98RON and Ultimate is 97RON. But why didn’t the fuel with increased RON rating have the expected effect?

Sandford says modern engine management computers can automatically adjust the ignition timing — to ensure the spark plug ignites the fuel at the optimum moment — if a fuel with a lower-than-normal octane rating is used. However, if better-quality fuel is used, the computer will not normally automatically alter the timing to give more power.

We may have only been testing one car over one gallon of fuel, but the results certainly suggest the implication that all cars will be immediately improved is wildly overblown.

Shell has already run into trouble with this. In February this year the Advertising Standards Authority upheld complaints against the claims Shell was making in its adverts, including that Optimax gives “an extra burst of power just when you need it”.

To be fair to the oil giants, they make another key claim about Ultimate and Optimax — that they help keep your engine clean and reduce emissions as well as boosting performance. Detergents within the fuels, they say, significantly reduce deposits on inlet valves and in carburettors. Our test was to see if there was an instant boost — we couldn’t test the fuels’ long-term cleaning power. But after thousands of miles a clean engine with fewer deposits may well perform better. “We wouldn’t expect to see a benefit over just one gallon of fuel,” said a Ford spokesman, “but using these fuels regularly is going to give you benefits.”

Both Shell and BP said they stood by their claims and had carried out extensive tests to back them up. A spokesman for Shell said tests on 37 cars on the British market found most showed benefits in acceleration and power, and one in eight customers was now buying Optimax. BP said that despite producing leaflets saying Ultimate “starts working from the first tank” they had never intented to suggest the fuel gave an immediate boost from first use. In a statement BP added: “The magnitude of the benefits vary from vehicle to vehicle and full performance benefits increase with distance driven. Because of this, short-term tests will not accurately demonstrate the full benefits of the fuels. However, the test data did also show some immediate benefits on most vehicles.”

Over the long term then, these super fuels may have benefits, but as our test shows you shouldn’t expect a fill-up with the pricier fuel to turn your Fiat into a Ferrari, or to respond as Popeye would after a good dose of spinach. and its sister non-profit websites,,,,,, and are owned by John Donovan. There is also a Wikipedia feature.

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