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djcool

BP Ultimate Diesel - 10k Review

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I've been using BP Ultimate Diesel in my tuned Volvo D5 for the past 10,000 miles and thought I'd post some comments on it.

Firstly - the cost. Most people are taken aback that I will pay an average of 4-5p a litre over the top of regular diesel. But on an average fill up of 55-60 litres, this only works out as less than £3.00 per tank! Hardly a lot, is it?

The engine runs a LOT smoother at idle, much less diesel clatter. On acceleration, the engine produces a much more linear feel to the acceleration. I wouldn't say it has any performance benefits, but it just makes the car a bit more enjoyable coming from ultra-smooth petrol models previously.

It seems to have given me slightly better fuel economy. Only slightly, though. On average, I was getting about 44-45mpg running regular diesel. Now I'm getting an average of 47-48mpg (calculated - not trip readout) for the same type of driving. This gives me an extra few miles per tank but probably not enough in itself to make up the difference in price.

BP Ultimate contains a variety of additional additives that are supposed to clean the engine and do a variety of other magical things. Can't say for sure that these are working (?) but the engine doesn't produce any black smoke, even at full throttle - and thats with the car tuned too.

I was forced to put in a small amount of Shell Diesel Extra a couple of thousand miles ago, and the car ran really roughly and produced quite a noticable cloud of black smoke upon start up. In addition, the fuel consumption was back to around 42-44mpg. Once I switched back to Ultimate order was restored and the mpg went back to 47-48mpg average.

I'd definately say it was worth it, and I won't run anything else in my car now unless I'm absolutely forced to!

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Totallt agree with your findings, have had the same results but only by sticking with BP Ultimate and not mixing at all.

Both cars much smoother and more responsive. The cold start up does not seem to be as noisy either.

Merc ML 270 and Golf MkV 2.0 TDi 4Motion

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I went with Ultimate for 6 months last year, and noticed no gain in MPG, torque or power gains compared to Shell Extra Diesel. Stuck with Shell ever since, does the same job, but isn't as expensive. 169144-ok.gif

Texaco is supposed to be the Diesel with the highest Certene rating, Millers Diesel Power Plus can be added to give the cleaning properties of the said fuels above.

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I used Texaco once but as reported on this forum it seems to make the VAG TDi engines lump and suffer from poor starting.

From the BP web site :

Guaranteed 55 minimum

BP Ultimate Diesel has the highest cetane number in the UK at a guaranteed 55 minimum and typically higher. Ordinary diesel sold in the UK has a cetane number of 51, according to European specification requirements. This big difference in cetane quality means that BP Ultimate Diesel actually burns better than ordinary diesel so you can expect your engine to deliver improved performance and better fuel economy, while producing fewer emissions.

What improved cetane value means for your diesel engine :

Noise :

The noise produced by a diesel engine is a combination of combustion noise and mechanical noise. Fuel properties can affect only combustion noise.

In a diesel engine, the fuel ignites spontaneously shortly after injection begins. During this delay, the fuel is vaporizing and mixing with the air in the combustion chamber. Combustion causes a rapid heat release and a rapid rise of combustion chamber pressure. The rapid pressure rise is responsible for the diesel knock that is very audible for some diesel engines.

Increasing the cetane number of the fuel can decrease the amount of knock by shortening the ignition delay. Less fuel has been injected by the time combustion begins and it has had less time to mix with air. As a result, the rapid pressure rise, along with the resulting sound wave, is smaller

Fuel Economy :

Here again, engine design is more important than fuel properties. However, for a given engine used for a particular duty, fuel economy is related to the heating value of the fuel. Since diesel fuel is sold by volume, fuel economy is customarily expressed as output per unit volume e.g., miles per gallon. Therefore, the relevant units for heating value are heat per gallon (Btu per gallon). Heating value per gallon is directly proportional to density when other fuel properties are unchanged.

Cold Starting :

When a cold diesel engine is started (cold start), the heat of compression is the only energy source available to heat the gas in the combustion chamber to a temperature that will initiate the spontaneous combustion of the fuel (about 750°F [400°C]). Since the walls of the combustion chamber are initially at ambient temperature rather than operating temperature, they are a significant heat sink rather than a heat source. And since cranking speed is slower than operating speed, compression is also slower, which allows more time for the compressed air to lose heat to the chamber walls. (A glow plug provides an additional source of heat in indirect-injection diesel engines.)

A fuel that combusts more readily will require less cranking to start an engine. Thus, if other conditions are equal, a higher cetane number fuel makes starting easier. As the compression temperature is reduced by variables like lower compression pressure, lower ambient temperature, and lower coolant temperature, an engine requires an increasingly higher cetane number fuel to start easily. Research indicates that fuels meeting the ASTM Standard Specification D 975 cetane number requirement of a minimum of 40 provide adequate cold starting performance in modern diesel engines. At temperatures below freezing, starting aids may be necessary regardless of the cetane number of the fuel.

Even after the engine has started, the temperatures in the combustion chamber may still be too low to induce complete combustion of the injected fuel. The resulting unburned and partially burned fuel is exhausted as a mist of small droplets that is seen as white smoke (cold smoke). This situation normally lasts for less than a minute, but the exhaust is irritating to the eyes, and can be objectionable if a number of vehicles are started together in an enclosed space. A fuel with a higher cetane number can ameliorate the problem by shortening the time during which unburned fuel is emitted to the atmosphere.

End of science lesson

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I've nearly always used Shell Diesel and I've never noticed a difference with BP Ultimate. I've always heard Shell Diesel is equivlant in spec to BP Ultimate anyway (and obviously cheaper)

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[ QUOTE ]

I've nearly always used Shell Diesel and I've never noticed a difference with BP Ultimate. I've always heard Shell Diesel is equivlant in spec to BP Ultimate anyway (and obviously cheaper)

[/ QUOTE ]

After writing the above review my local station has shut down, meaning I had to fill up with a tank of Shell Diesel Extra this afternoon.

I think the Shell Diesel Extra I tried before was just regular diesel, as it smelt completely different and so far no complaints with this tankful. Will pop in some Millers Diesel Plus tomorrow too 169144-ok.gif

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