Is there any real advantage in buying the higher spec (?) petrols like BP Ultimate ?
What do they do for the car to justify the extra cost of them.
Edited by Pugugly on 03/08/2008 at 22:46
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They keep the inside of the engine a lot cleaner and working more efficiently, which in turn provides improved economy, improved response, improved reliability, and less pollution.
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Allegedly.
Do some forum searches on here for the subject and you will find countless threads supporting and criticising premium fuels.
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.......... you will find countless threads supporting and criticising premium fuels.
My car's handbook says there is nothing to be gained by using them in my car, and I treat my car's handbook as the definitive authority.
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Marketing snake oil people who use it and say its its good are really people who don't like to admit they are being conned a salesmans dream.
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You can't dismiss this any more than you can endorse it. It depends on which benefit you are talking about, what car you drive, and how you drive it.
In terms of improved combustion chamber and valve cleanliness, I have read reports in many car magazines which back up these claims, based on their long term test fleets and borescope examinations of the combustion chamber areas on a before and after basis.
Whether there's any tangible performance or economy benefit from the higher octane rating however, is much more engine dependent. It depends on many aspects of the engine's design, from the compression ratio and induction method, through to the sophistication of the engine management system.
Based on tests that are as scientific as I could possibly conduct in day to day use, I can report that my Volvo S60, whose manual says to use the highest octane fuel available for maximum performance and economy, gets an average of 2mpg more on 99RON Tesco or Shell fuel, and feels perkier on part throttle. However, neither of these justify its extra cost, in my opinion.
A friend who has a Mitsubishi Evo 8 FQ300 has been forced to use 95RON on a couple of occasions, and reckons it destroys the performance and response of the engine.
Another friend who has a 1.4 Fiesta claims it makes no difference at all, and he's almost certainly right.
Car, and owner dependent.
Cheers
DP
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Correct DP
I have used Shell Optimax and now V-Power for years. For most cars the difference in performance is nil and economy likewise, although the engines tend to be smoother. For some performance cars, there is a sharpening of throttle response but I havenot done the maths on the economy.
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On cars like the Impreza Sti and Mitsubishi Evo it has worthwhile power benefits as magazine and tv programmes have shown. In an 'ordinary' car? Little if any difference day to day but perhaps better detergents etc. may show benefits in the long term,particularly with diesels.
Unfair to brand it snake oil though.
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As above -- for some cars (especially with high-output turbo- or supercharged engines) the manufacturers specify the use of 97 / 98 octane fuel, otherwise the ECU will retard ignition timing and boost, reducing peak power.
But if your manual does not specify use of 97 / 98 octane fuel, the performance benefit is likely to be slim to none, although the added detergency of these fuels may clean things up a bit.
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I run the bike on V-Power because it keeps the carb jets cleaner than the regular sort, and it definitely runs more smoothly and with better mid-range than anything else.
I have wondered whether compression ratios had a part to play here, having read many years ago that anything over about 10.5:1 would perform better on higher-octane fuel - the bike is a nudge over 11:1.
The Panda 100HP gets boggo 95-octane and likes it - less particular about using a specific brand than I used to be but it tends to be 50% Shell, 35% BP and the rest Texaco.
My mother tried about 3 tankfuls of V-Power in her 100HP once it was run in (so that we wouldn't confuse loosening engine with increased poke from the fuel grade) and reported no discernible difference other than increased cost of a tankful, so I haven't bothered.
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Several experiments by various institutes (including Top/Fifth Gear, Motoring magazines etc.) have confirmed that unless you drive a high performance sports car, premium petrol won't add any value!
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