The Truth About Premium Diesel Fuel

The truth about premium diesel

Premium diesel versus the standard stuff … is there a real benefit here, with the good stuff, or is it overwhelmingly marketing BS?

Free audio.jpg

My recent report on premium unleaded petrol (that's gasoline, if you’re not from around here) was like a red flag to a bull. And by ‘bull’ I mean ‘diesel vehicle owner’ - many of which fine upstanding citizens wrote somewhat literately to enquire about the merits of premium in the diesel domain.

See also the facts about octane rating >> and petrol versus diesel >>

Electrofiction said:

 
"It'd be great if you could do a similar video for premium Diesel, the stench of bullshit from the fuel companies marketing departments is frankly breathtaking... Surely there's a nut or two to bust there?" - Electrofiction
 

Mark Emerson chimed in:

 
"What about premium diesel fuels, how do they work?" - Mark Emerson
 

INSIDE THE DIESEL ECOSYSTEM

 The fuel ecosystem is an unholy alliance between carmakers, fuel companies and asleep-at-the-wheel regulators (here in Australia)...

The fuel ecosystem is an unholy alliance between carmakers, fuel companies and asleep-at-the-wheel regulators (here in Australia)...

We should go the full Sir David Attenborough and look at the ecosystem, in which an unholy trinity rules the diesel roost. You’ve got the vehicle manufacturers, the fuel companies and the government. A triangle of weasels, packed tight with mutual distrust and tri-lateral contempt.

Yet the vehicles are useless without the fuels, and the fuels have no purpose without the vehicles. And of course without the government there would be many more unemployed lawyer arseholes on the street, begging in bad Armani. So you can see this is a perfect system. Heaven, only on Earth.

Vehicles are designed to run on a particular kind of fuel - and those particulars are defined by a technical standard. The fuel is manufactured to meet that standard. And, hypothetically, the government cracks the whip. And here in ‘Straya, by ‘crack the whip’ I mean ‘fall asleep at the wheel and ensure that our fuel quality is among the shittest in the developed world’. So thanks a lot for that, regulators.

THE LEGISLATION

Here in ‘Straya the applicable standard for diesel is driven by a piece of legislation with the catchy name: Fuel Standard (Automotive Diesel) Determination 2001. Kinda says it all there - asleep at the wheel, but only for the past 17 years.

The original clay tablet (above) - click to enlarge

This document - still preserved in its official clay tablet form in Parliament House, Canberra - lays out the various environmental and operability standards - the physical properties of diesel. And all automotive diesel must meet those requirements or it may not be sold.

In total there are 19 different physical properties in the standard for diesel - things like cetane number and cetane index (which is - kinda - like octane rating for gasoline).

There’s density, viscosity, lubricity, conductivity, water content and flashpoint (attention fez-wearing terrorists everywhere: diesel is a crap fuel for a Molotov cocktail - flashpoint 61.5 degrees C - which is also why it’s so much safer for remote area refuelling from a jerry can - just saying).

There’s also limits for impurities in that legislation - five per cent maximum biodiesel content (which is undeclared if it’s in there). Ash, carbon residue, water and sediment, and of course: sulphur content (10 parts per million - currently). That’s almost a homeopathy treatment dose for sulphur, right there.

The diesel fuel quality standard lays out the complete list of legislated diesel properties >>

The point is: Your diesel engine is designed to run on diesel fuel that meets this standard. And it cannot be sold here unless it meets the standard. And this means the truth about premium diesel is 95 per cent marketing bullshit. Knock me over with a feather.

TRUCK DIESEL? WHAT THE?

 With trucks these days featuring the latest diesel technology and costing hundreds of thousands of dollars a pop, there is no way 'truck diesel' can be an inferior fuel

With trucks these days featuring the latest diesel technology and costing hundreds of thousands of dollars a pop, there is no way 'truck diesel' can be an inferior fuel

TheFullbrook says:

"At Caltex they have "truck " diesel and "premium diesel " what the heck is the difference? Also I have heard people say there is winter diesel and summer diesel?" 
- The Fullbrook

And 68404 - there’s a catchy name - parents must have been really prolific breeders, to have to start numbering their kids - he/she asks:

 
"Could you do something on 'Premium Diesel' vs 'Diesel'? There's also 'Truck Diesel' now being marketed… I thought all our diesel came off the boat from Singapore anyway and was low sulphur regardless these days? Can a modern single rail oiler ran happily on regular diesel?" - 68404
 

Yes, it can ran happily - your diesel will ran happily on any automotive diesel sold at a bowser. Truck diesel relates to the pump - which offers a fatter nozzle and a higher volume flow rate (and might not thus fit in a small diesel car) kinda like a Great Dane mating with a lap dog - there’s an image I hope lasts until the next time you re-fill.

Anyway, a contemporary modern long-haul truck is a very hi-tech healthy six-figure asset in a cutthroat business where every cent of operating cost really matters. Any suggestion that truck diesel might be in some way inferior is categorically nuts, when you think about it.

 Premium diesel conforms to the same standard as regular diesel, and the claims made about performance and/or economy are, essentially, nebulous bullshit

Premium diesel conforms to the same standard as regular diesel, and the claims made about performance and/or economy are, essentially, nebulous bullshit

PREMIUM DIESEL FOR POWER?

Unlike premium gasoline, which offers a higher octane rating than regular, and therefore a slight performance or economy benefit, there is no cetane rating jump with premium diesel. Engine performance will remain the same on premium diesel.

Premium diesel’s alleged benefits are … fluffy … at best. It has an allegedly superior additive package that is allegedly designed to make your engine allegedly cleaner. Whatever that means.

It’s BP’s piranhas all over again. Check out that preposterous BS here >> And it foams less on re-filling - not that the foaming of standard diesel has ever really shat me off in a substantial way…

LET'S GET PHYSICAL

Those motherlovers at Caltex actually make this official statement about the company’s Vortex Premium Diesel:

 
"Want a fitter engine? Try our new Vortex Premium Diesel. With upgraded magic ingredients (additives), Vortex Premium Diesel helps keep your engine healthier for longer, giving it a physical workout every time." - Caltex BS
 

I’m not kidding - they actually say that. Physical workout. In the immortal words of Olivia Neutron Bomb: Let’s get physical. Magic ingredients. Those marketing arseholes. I don’t think they were channeling their inner Arthur C Clarke:

 
“Any sufficiently advanced technology is indistinguishable from magic.”
- Legendary sci-fi author Arthur C Clarke
 
 Caltex's claims about the "magical" properties of premium diesel are unconscionable - even for the most overenthusiastic marketer

Caltex's claims about the "magical" properties of premium diesel are unconscionable - even for the most overenthusiastic marketer

I’m pretty sure that’s true - if we were to re-animate Copernicus, or James Cook, or Magellan, or Christopher Columbus, or Isaac Newton, and take them for a ride in a 787 Dreamliner and show them GPS, or even just make a telephone call from Shitsville to London, then I think they’d collectively conclude that we’re all wizards now.

But I don’t think Caltex is talking about that - sufficiently advanced technology comprising magic - I think they’re channeling the default marketing presumption that we’re all dead from the neck up. Channeling our inner bogans. (That’s like an Australian redneck, only substantially dumber.)

However, if you read the fine print it actually says that Vortex Premium Diesel - complete with alleged upgraded magic physical workout bullshit ingredients - merely conforms to the same standard as regular diesel, which your engine is designed to run on happily for about five laps of the planet.

BETTER PERFORMANCE?

Karl Pokorny says:

 
"Premium diesel is designed to produce less soot better for your dpf" 
- Karl Pokorny
 

And Jaco Olivier says:

 
"I did notice a small improvement (0.5L per 100) in fuel consumption by filling up with Premium Diesel. This is a different brand with measurements based on the car trip computer, so there is not much scientific proof here. On the topic of foaming, I am almost certain this is purely to do with the servo pump." 
- Jaco Olivier
 

All points here: Categorically bullshit. No statements about soot or DPF durability are made by fuel companies in relation to premium diesel. No statements about intrinsically greater economy or performance are made. Foaming is definitely a product of fuel composition, not the pump.

Shell says its Diesel Extra premium offering will help you (quote) “use less fuel” but there’s a disclaimer there should you read the fine print:

 
"Actual fuel savings and other product benefits will vary depending on age and condition of engine. Shell Diesel Extra is designed to avoid rising fuel consumption over the lifetime of your vehicle by helping to keep your engine running in accordance with manufacturer's specifications." 
- Shell marketing disclaimer BS
 

So it’s really just more nebulous bullshit wrapped around the non-specific ‘maybe’ benefits of an ‘alleged’ superior additive package. Which of course pumps up the price.

WINTER & SUMMER: MEET THE 'CLOUD POINT'

 There is an immense difference in diesel fuel chemistry at different geographic locations, and at the same location depending on the season - and it all has to do with the 'cloud point'

There is an immense difference in diesel fuel chemistry at different geographic locations, and at the same location depending on the season - and it all has to do with the 'cloud point'

Finally, there are a few different flavours of diesel across regions and seasons in Australia and they all have to do with a thing called the ‘cloud point’. If you want to understand cloud point, get a bottle of olive oil and put it in the refrigerator. Come back in an hour or so.

Olive oil starts to turn to wax at about four or five degrees C. Put it back in the pantry - the clouds of wax in the oil disappear. That’s the cloud point. Diesel does the same thing. And wax in diesel is of course undesirable because it doesn’t flow down the fuel lines. That’s kinda bad, if you want your engine to start.

So they tweak the chemistry of diesel to reduce the cloud point in colder regions according to a standard called AS 3570 - 1998. The maximum permitted cloud point is typically about 15 degrees C in warmer regions in summer. But it drops to minus three degrees in colder places in winter.

I only mention this because it might be a really bad idea to fuel up in Sydney or Melbourne in winter, and drive to the snow, shred some epic powder, get tanked, wake up nude, next to your wife’s sister and have absolutely no memory of what that means. More magic combined with a physical workout, right there…

 Getting the cloud point wrong (by driving to an alpine area with diesel from the city) is a good way to wake up stranded overnight

Getting the cloud point wrong (by driving to an alpine area with diesel from the city) is a good way to wake up stranded overnight

Then you will doubtless be utterly dismayed and appalled that your diesel getaway vehicle will not start, thus de-railing your plans for a cunning escape.

What has occurred is that the fuel in the capital cities at this time of year has a cloud point of zero or minus one degrees. And that’s what’s in the tank, doing a good impersonation of being quasi solid, because the ambient temperature is lower than the cloud point. And the temperature will doubtless drop even further when your disgraceful actions come to light.

If you had arranged instead to arrive at the ski fields in a low-fuel state and filled up - most likely with a fuel like Caltex Alpine Diesel - the cloud point of which is well below zero - your egress from this difficult extended family transgression would be far smoother. And I think we’d all agree, that’s preferable in situations such as these.

As things stand, in closing, I’d respectfully suggest that, if the clock on the chalet wall suggests that it’s time to come clean, even premium diesel’s magic will be ineffective. An imperfect place to commence your defence would be by offering a detailed summary of the fuel chemistry that lead to this somewhat unfortunate chapter in all of our lives.

CONCLUSION

I hope this report helps you save a few bucks on diesel henceforth by understanding that the main ingredient, by volume, in premium diesel is in fact marketing bullshit.


MORE REPORTS

John Cadogan18 Comments