As a diesel train driver at the Krøderbanen museum railway in Norway, and working with repair and maintenance of preserved diesel shunters, railcars and DMU's I think that the following might be of some help.

Low temperature fuel problems is usually caused by two things; water in the fuel or waxing of the fuel. Waxing (if that is the correct name for it in English) means that as the temperature drops vax crystals form in the fuel, thus clogging the filters etc. The temperature at which wax crystals form in diesel fuel is called its cloud point, and the lower the cloud point the better for cold-weather operation.

Problem 1, Water in the fuel

Water in the fuel will give you trouble from 0 degree centigrade downward. Always keep your fuel-tank full to minimise condensation. Drain your tank often, exchange your fuel-filter each autumn, and drain them now and then during the winter. The filters will collect not only dirt but also water, and then they quickly freeze up on you.

Problem 2, waxing of diesel fuel

In Norway diesel units, and motorcars, are run all year round and in temperatures reaching - 30 degree. centigrade and lower. To avoid the waxing problems the oil companies in Norway deliver their diesel fuel in (at least) two temperature grades.

"Summer grade" with a minimum operating temperature of approx. - 11 degree centigrade, and a "Winter grade" with a minimum operating temperature of approx. - 24 degree. centigrade. When this is not sufficient the operating temperature is lowered further by mixing paraffin in the diesel fuel. This can be done with any grade of diesel fuel, i.e. your "summer grade" can be transformed into a fully functional "winter grade" by adding paraffin.

Based on information from Shell here in Norway the operating temperature of the "summer grade" will be lowered approximately 2 degree. centigrade for each 10% of paraffin. The effect with "winter grade" is somewhat better; approximately 3 degree. centigrade for each 10% of paraffin. This way the operating temperature of the "summer grade" can be lowered to
approximately - 25 degree centigrade, and the "winter grade" can be lowered to approximately - 42 degree. centigrade. Refer to table 1 for details.

IMPORTANT: Whenever mixing more than 40% of paraffin in your diesel you must add TWO-STROKE engine oil to the fuel. This is because the lubricating properties of the diesel is destroyed when mixing it with large quantities of paraffin, thus you risk excessive wear or breakdown of your fuel injection pump if not adding some two-stroke oil, whereby the lubricating properties is upheld.

When mixing diesel and paraffin it is not sufficient just to pour the paraffin into your fuel tank. If you do this the paraffin and diesel will not mix well. The paraffin will then end up as a layer on top of the diesel fuel. Either you should stir it thoroughly after pouring the paraffin into the tank, or you should pour it down into the bottom of the tank by means of a hose. Personally I would recommend doing both, pour it into the bottom of your tank through a hose, then stir it.

Table 1: Diesel fuel operating temperatures

Diesel fuel	summer grade	winter grade	% of two stroke oil
opr.temp as sold	-11 dgr. C	-24 dgr. C	0 %
wiith 10 % paraffin	-13 dgr. C	-27 dgr. C	0 %
wiith 20 % paraffin	-15 dgr. C	-30 dgr. C	0 %
wiith 30 % paraffin	-17 dgr. C	-32 dgr. C	0 %
wiith 40 % paraffin	-19 dgr. C	-35 dgr. C	0 %
The following not to be used without the added two-stroke engine oil:
wiith 50 % paraffin	-21 dgr. C	-38 dgr. C	0,50 % t-s oil
wiith 60 % paraffin	-23 dgr. C	-40 dgr. C	0,75 % t-s oil
wiith 70 % paraffin	-25 dgr. C	-42 dgr. C	1,00 % t-s oil

If using diesel fuel with other clouding points then assume a lowering of the clouding point of 2 degrees centigrade for each 10% of paraffin.

Other measures

Use engine oil SAE 15W - 40 or 10W - 30 depending on climate. This makes for easier starting and reduced wear during the start-up and the warm-up period while you fully maintain lubrication at normal operating temperatures.

If not already installed then install coolant heaters on your engines. This will greatly improve the cold-starting abilities, and will also reduce wear. I think there are diesel fired systems available, but in Norway we use electrical heaters in the cooling systems of all our engines.

Always use ethylene glycol based antifreeze in your coolant. 30% will keep you safe down to approx. - 15 degree. centigrade, at the same time providing a sufficient corrosion protection. At the Krøderen line we use a 50/50 mix the year round, it keeps us safe down to approx. - 36 degree. centigrade during winter storage.

Hopefully this will help you with more trouble free winter operations. Some information about Krøderbanen museum railway and The Norwegian Railway Club is available on http://www.njk.no/~njk/kroeder/index_e.html and http://www.njk.no/~njk/index_e.html 

Bjørn Hall - by e-mail <bhall@online.no> 
home address Røssekleiv 37, Phone +47 32 85 04 63
N 3408 TRANBY mobile +47 911 26 507
Norway Fax +47 910 22 180

From Chris Bull (Dean Forest Railway):

If you have a word with your supplier, ours can be delivered during winter months to cope - how do you think farm tractors manage? Change your supplier to one that does supply it!

From Gavin Booth (Swindon Diesel Preservation Society & bus restorer):

FUELS/ SMOKE

Re. enquiry in Railcar on fuel additives etc. Firstly the reason DMUs are so smoky is that they spend much of their time idling, either when stationary or coasting, so that the engine is not working at correct load/temperature. Oil builds up in the pistons causing blue smoke when the engine is worked - especially if your cylinders/piston rings/valve guides are worn. This problem is worse on preserved DMUs where they seldom get a good "thrash" to blow the smoke out. Fuel additives may reduce any black smoke, but probably would not cure the idling-blue-smoke problem. A suggestion is use of thicker oil, e.g. 20/50 instead of 10/40, which might reduce blue smoke (it has worked on my buses) but it all depends on how worn your own engine is and how much it gets "thrashed".

Of course black smoke will be affected by the fuel pump settings (maximum fuel stop) and the condition of the injectors - check these before trying anything fancy!

(NB Black smoke= too much fuel; Blue smoke= Oil; White smoke= air in the fuel line).

On fuels, there have been various anecdotal stories of low sulphur diesel being bad for older engine designs; such as poorer power output, poorer injector lubrication, etc. It is probably too early to say yet however the AEC Society have investigated this matter with BP who advised that their "Greener Diesel" in tests gave the same power output and fuel consumption as many other diesel fuels; but advised that low sulphur diesel contains a lower content of aromatics. This in turn may affect fuel pump seals in older high mileage engines. The long term effects of low sulphur diesel on old engine designs such as 680s remains to be seen.

On additives, various smoke reducing additives are available. Some however are basically "cleaning" agents i.e. will burn off excess carbon in the engine. I surmise that in a worn engine this may make things worse - if the ring of carbon at the top of the piston bore is removed this could worsen the compression ratio. Other additives work by improving the way the diesel fuel is burnt and this may reduce black smoke, but I am as yet unsure if there are any side effects. I suggest the safest thing to do is stay away from additives meantime, until their use becomes more common when only low sulphur diesel is available in future. If anyone has any more concrete evidence of the effects of fuel additives, we want to hear from you.

It used to be a common (illegal on roads) practise to add paraffin to diesel. However beware this can reduce the lubricity of the fuel and in time could affect the lubrication of fuel pumps and injectors - some pumps and most injectors rely on the fuel going through them for lubrication. As these are high precision components (and expensive to overhaul), I do not recommend taking risks with them. Whilst a small quantity may be acceptable, it should not become normal practise. So, if trying this, exercise caution, and communicate the results to The Railcar.

From Trevor Daw (DMU Group (West Midlands)):

I have just read the latest TRA bulletin 44, where the matter of 'red' diesel fuel grade, otherwise know as 35 sec. Gas oil, is raised.

The oil industry nation-wide supplies winter grade fuel from October 1st until the end of April. This has been normal practice for the past ten years. The difference between the grades is the anti-waxing additive. The current specification should give protection down to 20c before additional additive is required. Most unlikely in the UK so far, unless of course we are about to commence another ice age!

At the Severn Valley Railway we always specify what grade is required, particularly if refilling our bulk tank in the early autumn. Judging when to order winter grade is fairly easy for us. Owing to demand brought about by our regular services. With three power cars each fitted with 2x85 gallon tanks. When full we are carrying 510 gallons, or in weight terms about two and a quarter tons. However, for operators with a smaller demand I can recommend they run the car tanks at a low level toward the end of their summer timetable. When new winter supplies arrive this will dilute the remainder of the summer grade and overcome the starting problem.

The 'wrong type of fuel' manifests itself more so, when trying to start a Smiths heater on a dew laden morning. This is to be expected because they were originally designed to run on paraffin. Years ago B.R. economy forced a change to using gas oil for heating from the engine tanks. But no one thought to specify a hotter type of glow plug. Our local trick to get them to fire is to clean the plug weekly. When striking up, you make a quick exit from the cab. A quick dash to heater and clasp a gloved hand around the air intake to restrict the inrush of air. Thereby giving the glow plug a chance to ignite the fuel oil. It also helps should a strong wind be blowing which can cool down the heating coil.

I am waiting to hear whether there are going to be any developments with respect to 'low sulphur' quality gas oil, which might benefit our movement. I suspect it has quite a low priority.

Further to the above notes, I have talked with a technical friend at the suppliers. To begin with, no LS gas oil is yet available from the refiners. There is no doubt that it will be issued at sometime in the future, could be within the next eighteen months. The new duty paid LS oil on sale at the service stations has replaced DERV as from spring of this year. This oil is less smoky and is making a significant contribution to lowering diesel exhaust emissions. Obviously this will contribute to improving the environment.

It has been pointed out that this new fuel is best suited to modern engines and their electronic management control systems. How it will perform on an older engine remains to be seen. It will have a similar effect as using too much choke in a petrol system. It will tend to dilute the lubricating oil. In the future we will have no choice but to use this new blend. However the recommendation is to continue using current gas oil until it is no longer available.

We as a national Railcar Association need to find out if the new fuel will damage engines, as has been suggested. I wonder if there are any members who operate busses fitted with the Leyland 680 type engines. How are they coping with the new fuel? Will we need to use a different specification of engine oil to compensate? It is a subject we must pursue and find the answer. Although we have time at present we must be prepared for the changes.

From John Crane (Heritage Railway Association & Railway World):

I have literature on low sulphur fuels (following the scares of the early low sulphur fuels of VERY high wear levels (30 hours running) - was in fact due to a very complex action).

Winter fuels, I have always believed that suppliers modified the fuel to suit the time of year - hence it is not a good idea to buy in bulk - this may be out of date with modern fuels.

re the car, with my first Peugeot (15 years ago) it said that Paraffin could be added in winter months EXCEPT IN THE U.K. - this being for taxation reasons. Instinct rather than knowledge tells me that adding petrol would be vary bad news - not least in terms of lubrication of pumps and injectors.