Interesting article about diesel (the fuel)

[kaanage]

It's a US 2007 article (Chevron) but the fundamentals still apply over here

http://www.chevronwithtechron.com/products/documents/Diesel_Fuel_Tech_Review.pdf

[bluey]

Major difference is that US fuel is horrible generally compared to ours. Low lubricity and low cetane diesels. Also low octane petrols. Their best "high performance" fuel is 95RON.

Anyone interested in how bad the fuel is can read all about the HPFP failures in USA and NHTSA investigation ongoing.

We are lucky to have a better quality of fuel here.

[Mysticality]

Their best "high performance" fuel is 95RON.

Interesting... I thought the "high performance" was RON97 and they measured slightly differently?

I know their RON91 equivalent is RON87...

[Diesel_vert]

In the US, gasoline pumps must be labelled by the fuel's anti-knock index (AKI), which is calculated using the average of the RON and MON, i.e. ( RON + MON ) / 2 = AKI.

The three most common grades of gasoline in the US are:

- Regular unleaded: AKI 87 (91 RON)
- Midgrade unleaded: AKI 89 (93 RON)
- Premium unleaded: AKI 91 (95 RON)

Premium unleaded with a AKI of 93 (98 RON) is widely available in many states, but very rare on the west coast.

[kaanage]

Major difference is that US fuel is horrible generally compared to ours. Low lubricity and low cetane diesels. Also low octane petrols. Their best "high performance" fuel is 95RON.

Within the context of that linked document, those differences are very minor and the diesel one is mainly to do with lower additive packages added post distillation in the US (ie the same as BP Ultimate vs 'normal' diesel down here, allegedly).

[kaanage]

In the US, gasoline pumps must be labelled by the fuel's anti-knock index (AKI), which is calculated using the average of the RON and MON, i.e. ( RON + MON ) / 2 = AKI.

Yeah, that confused me the first time I went over there and hired a car - I was thinking "What sort of çrap are they running?" and later found that their Regular was pretty much the same as ours.

[Diesel_vert]

Within the context of that linked document, those differences are very minor and the diesel one is mainly to do with lower additive packages added post distillation in the US (ie the same as BP Ultimate vs 'normal' diesel down here, allegedly).

While it is normal for refiners to add fuel additives into their products, the problem is the fuel standard for diesel in the US allows for a higher wear scar of 520 microns in the HFRR lubricity test, as opposed to the more stringent limit of 460 microns for European and Australian fuel standards.

Although it's a rather understated point in the document, major diesel fuel injection equipment (FIE) manufacturers have repeatedly expressed concern that:

It is expected that the useful operating lifetime of any mechanical component
will be adversely affected by fuel with a lubricity exceeding 460 microns.

- FIE Common Position Statement, dated 2004, 2009 & 2012

That's not to say all diesel fuel in the US will produce a wear scar larger than 460 microns, but there's no guarantee or requirement that it won't. It seems to me that it's an onerous and heavy burden on the consumer if one wants to ensure every fill up is with good fuel (as observed by posts made on the TDIClub forums).

Having said that, a splash of biodiesel does wonders for lubricity when added to diesel, even just at 2%.


Low cetane in diesel fuel affects driveability and emissions in different ways, but the issue of lubricity and equipment reliability is/was the big talking point.

[kaanage]

While it is normal for refiners to add fuel additives into their products, the problem is the fuel standard for diesel in the US allows for a higher wear scar of 520 microns in the HFRR lubricity test, as opposed to the more stringent limit of 460 microns for European and Australian fuel standards.

Yes but it is the additives that lower the wear scar, not further refining of the base product (as discussed in the Spicer report from a few years back).

The point is that the article does not greatly differ in how the crude oil ends up being refined for our diesels

[Diesel_vert]

The point is that the article does not greatly differ in how the crude oil ends up being refined for our diesels

Well, I admit I got mixed up in discussing the finished product as seen by the consumer - but I take your original point.

I'd probably go as far as saying the refining process for petroleum diesel and the various complexities would be broadly similar across the developed world, but it's a very informative document nonetheless.

[kaanage]

I'd probably go as far as saying the refining process for petroleum diesel and the various complexities would be broadly similar across the developed world, but it's a very informative document nonetheless.

Absolutely agree with you here and that is why I posted the link to the article. A petrol article that was sourced from the UK or Europe would be equally applicable to us. I guess it was the word major in bluey's post that I felt was unwarranted.