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Has anyone any experience of the recently introduced Shell petrol called OPTIMAX it boasts a higher octane level, the product is not yet widely available. Is there another oil company that brews an equivalent ???.
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I think they have just cleaned the fuel up a lot (less muck in it to foul injectors etc) and probably added a few oxygenates in the process. They do claim to have increased the octane rating to above 98, but given 95% of all cars manufactured in the last 10 years are built to run on 95RON unleaded I don't believe this particular aspect will have any effect whatsoever on performance in a normal car. I think they have intended it to replace super unleaded and have probably done so because super unlead has such a bad press.
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Richard, use the search facility to find earlier threads on this subject. Basically, any car designed to run on 98 octane fuel (or one with a knock detector fitted) will benefit, although much will depend on driving style. Cars designed specifically for 95 octane fuel and without a knock detector will probably not see any benefit. Personally, I've been running a 1.6 golf for the past month on it and have seen a very slight improvement in fuel consumption (1-2mpg) and mid range punch over super unleaded. Its not much but its the same price as super unleaded so no penalty in cost. The difference between 95 octane unleaded and 97/98 octane is much more noticeable in terms of performance and fuel consumption.
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I'm always amazed how anyone claims they can actually MEASURE 1-2mpg difference in fuel consumption accurately without testing equipment. There are so many other variables in there from the weather to the traffic to how the driver feels that day and the accuracy of the clock allied to tire pressures and who knows what else. Seems to me a psychologist could make something of this! My Harley seems to hate this particular brew, maybe that's me projecting the comments others have made about it!
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it's easy growler, the car has a constant fuel consumption read out giving actual consumption (to the last 30 seconds) , average (over that particular journey) and long term average over the accumulated mileage of the vehicle (or since it was reset). The long term average has increased from 36.5 to 37.8 since using the fuel, but you are right that other factors come into play and cold be distorting the figures. Hence I went back to using super unleaded for a short while and saw the consumption change again, but it's too small to worry or argue about and could be a spurious result. Either way the consumption is no worse and the car feels better. Don't forget that this car was designed to run on 98 octane and the manufacturers performance figures are given on the assumption that you are using it. By using 95 octane, everything is a compromise (cheaper fuel but higher consumption and slightly flatter performance). Ultimately it comes down to personal preferences and economics. Given the price differential between super and optimax (nil) and between super/optimax and u/l (5p, ish) and the better fuel consumption, it is cost neutral and I prefer the performance.
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