BP Ultimate Diesel for Perth People

[Greg Roles]

Well BP ultimate diesel happened today on the northside, at the two BP's I drive past at least. Filled up today, so I'll see how she goes over the next week. Cost seemed to be "about" the same as usual...

So what IS the new cetane rating of it anyhow? The brochure beside the pump is all consumer marketing, cleaner engines blah blah....

[Logzy]

BP Ultimate Diesel (10ppm sulphur)has a guaranteed cetane rating minimum of 50
The ULS (10ppm sulphur) Diesel has a guaranteed cetane rating minimum of 48

Wonder if that 2 cetane difference is worth the extra cents ?

[Greg Roles]

WTF does cetane mean anyhow ?

Driving around today on the new "super-diesel" I noticed SFA.

It DID however do a DPF regeneration cycle within the first few minutes of driving off, when it was barely warmed up. That was a first. Perhaps the detergents dumped a bit of crapola into the DPF???

[Logzy]

Cetane is the diesel measurement for its combustion quality, similar but not exactly the same as, an octane rating is for petrol.

[bluey]

BP claims typical cetane of 55-60 for ultimate compared to typical of 51 for normal. Theoretically, higher cetane ratings alter combustion and are meant to result in reduced diesel clatter.

The link was to an old spec see latest ( Feb 2008 ) BP Ultimate specification.


I suspect most of the claims of BP Ultimate diesel's performance improvements are due to superior detergents cleaning injectors, in which case it is more likely to help an old engine.

[greygolf8]

So is adding detergents different to adding some bioD ? If u need detergents, does that mean normal diesel clogs injectors (eventually ) ? mmmm confusion or just marketing ?

[bluey]

From what I've read, bio has worse fuel consumption than dino. Low sulphur diesel is more likely to leave varnish and gum deposits on injectors, according to this article on diesel truck maintenance.

[bluey]

BP Ultimate Diesel experts forum was interesting.

In the final analysis, it looks like BP Ultimate Diesel is standard diesel + "secret" additive package:
1. nitro type cetane improver
2. injector cleaner
3. anti foam to prevent splashback
4. corrosion inhibitor

Cost is meant to be about 1c/L dearer than standard. Performance improvements are meant to be better in smaller car engines because they operate on higher load and revs.

[cetane]

I guess with a username like mine I had better provide a link to info about cetane rating.

One thing worthy of note is that it isn't just a case of "the higher the cetane number the faster you go...." as performance plateaus when you get over CN55. Really, it's basically a measure of the fuel's ignitibility under compression, specifically the time period between the start of injection and start of combustion. Higher cetane fuels have shorter ignition delay periods than lower cetane fuels. IMHO even the slightest error in POIT (point of ignition timing) has a much more profound effect on performance than cetane rating. This is perhaps why modern computer-controlled diesel engines get so much more from a litre of fuel in both performance and economy than do older, mechanically injected motors.

http://www.answers.com/topic/cetane-number

[gregozedobe]

I suspect most of the claims of BP Ultimate diesel's performance improvements are due to superior detergents cleaning injectors, in which case it is more likely to help an old engine.

I'm inclined to agree.

It was stated many times that the full performance benefits were only gained after using 2-3 tankfulls of the new fuel (ie after the cleaner had a chance to clean up the injectors). If it was due to the increase in cetane then the improvement would be there with the very first full tank.

Results will obviously vary depending on the engine and how old/new it is and whether the ECU can take advantage of the higher cetane or not (I guess in that way it is similar to using higher octane petrol).

Maybe I should use an injector cleaner additive once or twice a year (who knows when we'll get BPs new wonder fuel in a small market like Canberra ?)