diesel

Maybe the diesel shop have answered your query.
I have had numerous diesels of varying size and have never used additives.
Common rail is much more delicate that older diesels so I do not even contemplate additives. Excellent filters eliminate most problems.

Yes interesting. I've always used a fuel conditioner in my diesel. A bloke asked me once if it did any good and I said "I dunno mate but it makes me feel good".

Anyhow this prompted me to have a talk to our local diesel service and their diesel technician reckons people who travel and can't always guarantee the quality of the fuel should always use an additive. He recommended Castrol Fuel Doctor!

Provided you are buying distillate from an outlet that dispenses high volumes and performs regular maintenance on their storage tanks, an additive should not be necessary. The biggest danger is bacteria and fungus that can form and grow at the interface between the diesel fuel and any water that exists in the retailers storage tanks. If present these microbes can be transferred to vehicle tanks where it continues to grow and multiply eventually causing blocked filters and worse if it finds its way in to the fuel pump and the injectors. An additive containing a biocide will kill the bacteria but the difficulty that you face is that you don't know when you will need it until it is too late when you start experiencing blocked filters, clogged fuel lines, etc. The only way to guard against this is to add it to your fuel at the correct rate as a preventative measure if traveling in remote areas where dodgy fuel is a possibility. Check first with your vehicle manufacturer to ensure what additive you propose using (if you decide to use one) that is is safe to use in your make of vehicle.

I use a biocide in my 200 series after a nasty experience with a boat I had, which had four 400 litre tanks. We actually had to take the covers off and put a small bloke into the tanks to dig the bacterial growth out. It grew like seaweed everywhere and would actually block 6mm lines.
It's okay if it is not disturbed. But go over some bumpy roads, or in my case a bumpy sea, and it all breaks loose and blocks everything.
I have heard of 200 series, which have a 138 litre tank, showing no problems when used around town with long waits between fills, but blocking up filters during a trip over rough roads.
I think a biocide is good insurance and add to the 180 litre tank at every fill. Adds about 2 cents a litre to the fuel cost.
Keith

Hi Barry , Made a difference in the Hino and the cummins 500, but no real difference in the Isuzu. used it in the 80 series for 20 years no probs at all, it made no difference to the Dmax and as yet not been game enuf to try in the 200 series.
I did do an injector in the cummins but to be fair to it was around the 600,000K mark. I have had no fuel probs in the 4'bs but then I have always had 2 good fuel filters and change them every 10,000k's.
Hope this helps a bit. cheers bass

There's nothing that will get people going into different camps, more than asking about fuel additives.
Some will swear by their favorite additive, some will say you don't need them, some will say they tried them and noticed practically no difference.

Even the experts are seriously divided. Motoring organisations will tell you additives are snake oil - but some manufacturers will state outright that injectors and fuel systems need regular cleaning.

The RACQ is against any form of additives - stating that buying "good quality" fuel is paramount and regularly changing filters is important.
They state that diesel injectors aren't all that prone to buildup and fouling. However, in my long experience, the opposite is the case.

RACQ - Diesel injector cleaning

I was in the Isuzu dealership a little while back (yes, giving them my hard-earned moola - LOL) - and they are advertising that regular CR injector cleaning is crucial for good performance - and they even have a 2-page handout article on the counter, explaining why it's important to have Isuzu CR injectors cleaned every 100,000 kms.

A simplified look at injector operation

There are a number of major differences between the old, simple and basic, mechanical-operation, Bosch-type injection systems and the newest CR injection systems.

Perhaps a side-by side comparison is important.

Mechanical injection -

1. Simple, with injection pump pressure causing the injector pintle to unseat, against strong spring pressure, to allow fuel injection.
2. Low pressure operation - 1500 to 2500psi (10,350kPa to 17,240kPa).
3. Fairly fine tolerances - around 1/10,000 of an inch (0.0001" or 0.00254mm)
4. Injector orifices - 1 to 4, ranging from 0.020 to 0.010 inch (0.5mm to 0.3mm)
5. One long steady fuel injection stroke that lasts around 100 to 250 milliseconds, and which commences either just slightly before or right on TDC.

CR injection -

1. Complex, with multiple mechanical and electronic components, and injection being controlled by an electronic solenoid that causes the pintle to unseat to allow fuel injection.
2. Very high pressure operation - 25000 to 30000psi (172mPa to 206mPa).
3. VERY fine tolerances - around 1/20,000 of an inch (0.00005" or 0.00127mm)
4. Injector orifices - 6 to 8, ranging from .003 to .004 inch(0.08mm to 0.11mm)
5. Multiple, extremely fast fuel injection pulses (4 up to 8) that lasts around 30 to 50 milliseconds, and which commences either just slightly before or right on TDC - and which injection pulses CONTINUE to happen, as the piston travels downwards on the power stroke.

So you can see that CR injectors under under vastly more stress, vastly increased numbers of operating cycles (for a given number of engine rotations), and they operate with tolerances so fine, they need 100% perfectly clean fuel, and the correct level of lubricity in the fuel.

Now, in the bad old days, sulphur was a naturally-occurring ingredient in diesel fuel, and it was left in, because it aided in fuel injection component (and engine component) lubrication.
In essence, sulphur provided a protective layer of sulfides to metal components that helped prevent metall galling and seizing.

With the drive towards very-low-sulphur content diesel to reduce exhaust pollution, diesel lost a lot of its natural lubricity - so the refiners have had to add other lubricity additives to compensate for the loss of the naturally-occurring sulphur.

Now, we're never told how good those lubricity-improvers are, or in what quantities they are added, or how much they vary between the various brands of fuel-floggers.

One has to keep in mind that our refined diesel comes from numerous sources.
It is refined in Australia (about 40% of our total consumption, from memory) - and the rest comes ready-refined to Australian Fuel Standards, from Japan, South Korea, and SIngapore.

This is where it all gets a little murky. Australian Fuel Standards are pretty good, on a worldwide basis - but that doesn't mean that refiners can't utilise additives that meet the fuel test - but don't perform as well over time or in varying conditions, as other additives used for lubricity.
There is a measurement standard for diesel lubricity in the Australian Standards.

This lubricity measurement is purely a timed test. A steel ball and a flat disc are submerged in a temperature-controlled bath of the diesel to be tested, a light load of 2 Newton is applied, and the ball is reciprocated at speed across the flat disc at a set stroke and frequency.
The wear on the flat disc is measured after 75 minutes and average (mean) wear levels are calculated.
Our Australian Fuel Standard follows the European Standard, and a wear level of 0.460mm maximum is allowed for 500ppm ultra-low-sulphur-level diesel.

Australian Diesel Standards

The problem with the lubricity test is that it is a laboratory test - and it doesn't necessarily represent real-life fuel use - where temperatures vary enormously - where fuel is constantly subject to contaminants - and where fuel gets stored in numerous, less-than-ideal storage arrangements.

Many older service stations have tanks that are contaminated with corrosion, with water (from condensation and flooding) and even fine mud (from flooding).

Fuel station bowser pumps usually have basically satisfactory filters to remove contaminants - but if there is water and other contaminants in the tank, these are quite capable of degrading the additives in the diesel purely via simple chemical reaction.

One thing is for sure though, there is a substantial variation in fuel quality depending on the fuel brand, and the service station it comes from. Older service stations with tanks that are 30 or 40 or even 60 years old have to be very suspect for fuel quality.

Speaking personally, I like to get my fuel from newly-built servos that have substantial, and newer and better arrangements for fuel tank protection, from corrosion, and from water and dirt ingress.

Then, besides the fuel lubricity quality angle, we have the "carbon-and varnish-buildup-in-use" angle.
This is one feature of diesel engine operation that is a given and constant factor.
Injectors develop carbon buildups on the tip and in injector orifices - and they develop varnish and gum deposits on moving components, that are caused by heat cycles and chemical contaminants in fuel that slip through even the best filters.

On that basis, the use of a fuel additive that removes buildups of carbon, varnish and gums after prolonged engine use (say 100,000kms) is a pretty worthy idea.

The use of an additive on a constant basis, that is reputed to improve cetane ratings, lubricity, and fuel burn, is something that should not normally be needed - and which the true value of, is buried in untruthful "marketing hype", excessive cost of these additives - and the fact that these full-time additives are usually accompanied by the manufacturer/agent urging others to become dealers - thus indicating to me that they are highly profitable lines, with huge profit margins for anyone flogging them.

One only has to investigate the chemical structure of these full-time additives to find that many contain around 60% of their makeup in the form of common naptha-based solvents such as Stoddard Solvent (White Spirit, Solvent 150, Varsol) - which largely sell for about 1/4 to 1/3rd the price of the fuel additive!

Cheers, Ron.

The sulphur content in Diesel fuel is not there anymore which was a factor with lubricity and some argue that a good quality additive helps with that if needed. I think additives are a necessary in a marine diesel environment for example but in a late model common rail vehicle I would think the brand of diesel makes a difference, Caltex Vortex Diesel I find superior to normal diesel. BP make an ultimate diesel in WA that is not available in Victoria for example.

Think about all the transport that runs about this country and don't use any aftermarket additives. All they do is have a very complete record of their fuel fills from normally one supplier.
Those suppliers don't want any problems coming their way from broken engines and downtime as it costs them plenty and their is no recourse because of the fuel and service records.

These same vehicles/tractors/earth moving equipment are now mostly all common rail and clock up some very big hours and kilometres.

Diesel fuel has changed heaps since the old days. Filtration, keeping tanks full and not short running the diesel engine are your best friend.

It's rather interesting, that in the U.S., there were major problems when low-sulphur and ultra-low sulphur diesel was introduced.

Substantial numbers of rotary-type diesel injection pumps were damaged by the loss of the sulphur content - and many users made successful claims against fuel suppliers for recompense.
However, diesel fuel in the U.S. is refined to poorer fuel standards, with a lot more variation, than we have in Australia.

Rotary-type fuel injection pumps need diesel fuel with excellent lubricity qualities, because of the intense metal-to-metal loads placed on the components, such as rollers, cam plate and plungers.
The rotary Stanadyne injection pump as fitted to the 6.2L and 6.5L Chevy V8 diesel is particularly prone to short life if the fuel has inadequate lubricity.

Interestingly, the additives added to diesel fuel to improve lubricity are fatty acids - more correctly, they're called FAME - Fatty Acid Mono Esters.
These are usually fatty vegetable or animal oils treated with alcohol, whereby the FAME is created via chemical reaction with the alcohol, forming the Ester.

There's an interesting article in the link below (part of a chapter of a book), whereby two Greek chemistry professors experimented with using various essential oils, as lubricity improvers.
These essential oils experimented with, are the common ones we know - grape seed oil, peach kernel oil, camomile oil, laurel oil, carrot seed oil, castor oil, eucalyptus oil, pine oil, lavender oil, and rosemary oil.

The experiments showed that a number of these oils added to diesel improved the fuel lubricity.
However, the substantial number of ingredients in a number of the essential oils often worked against the particular oil, for improving diesel lubricity.

What is also of interest in the article is that the professors state that it's not the actual sulphur in the fuel that provides the lubricity - it is polar compounds (i.e. - negatively or positively charged compounds), associated with the sulphur, that provide the protective coating to the metal surfaces.

The chemistry of fuel and refining, obviously often has a lot of the refining chemists scratching their heads, because of the extreme complexity and amount of the chemical compounds in fuel.
One thing is for sure though - improved additives and improved fuel quality is rarely pursued by oil companies unless there's money in it for them.

Diesel lubricity experiments

Cheers, Ron.