Does diesel go bad in the sense that petrol loses octane, does deisel lose cetane?
Just wondering as a car is getting difficult to start, the engine is all good as are ancilleries. The diesel has been in the tank over 4 months now. Could it just be turning bad?
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If it's been in their 4 months, it's probably summer diesel, and not winter diesel.
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??? never heard of it changing with the seasons, enlighten me please.
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In temperatures below about -4C, diesel waxes up and will block your fuel filter.
To stop this, fuel companies put in an additive in the winter.
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Summer diesel will give you better performance and economy than winter. This is because it naturally has a higher heating value than winter diesel. The heating value (not cetane) is what produces power, it is the paraffins in it which make it burn hotter.
But as temperatures drop, summer diesel begins to gel and crystallise (that's the paraffins again) and can not flow through your engine's fuel system. On the other hand, winter diesel will flow well below zero.
So it is a trade-off. You can't have both a true cold weather fuel and a best performing fuel.
This is in addition to any degradation which I'm sure must happen, in fact sometimes you can even get bascteria blooms in old diesel, which looks like lots of mucous has been added to the fuel!
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Temperatures in most of the country havn't been below zero for some days so I don't think it will matter whether you have summer or winter fuel.
So if your having trouble starting it's most likely to be a faulty glow plug or two, or possibly the battery is low as the car hasn't been far in the last 4 months.
Does the car start ok if the engine is warmed up a bit?
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I was just wondering if winter diesel was the reason why my 1.9ZX (non turbo)Diesel has been losing economy lately. In september / October time I was getting about 500 miles to the tank - but now I am only getting about 400 maximum to a full tank of fuel. Does anyone know what I should be getting to a tank on this car? I was reckoning around 500 miles.
The car is serviced regularly and has had new air and diesel filters but this didn't make much difference, although it did improve things slightly. I have also tried a good injector cleaner (Millers) and a long high speed motorway run - but again not much difference was made to the economy.
I was wondering if the injectors are at fault as the car has done about 82k on its original injectors - or would it be the change over onto winter diesel from summer - as I have noticed that fuel from some petrol stations seems to offer better economy than others.
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Winter and summer diesel, are merely marketing terms, number 1 and number 2 diesel are blended in varying ratios and have additives added that suit the weather, time of year, country and region etc....
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I note that there have been a number of posts recently about poorer diesel fuel consumption, maybe Schnitzel has given us the answer.
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Hi there,
I would have thought you would get a bit more than 500 miles, especially if it has a 60 litre tank and depending on your driving style of course!
I have a 1994 Peugeot 306 Diesel (heavier than a ZX) with the same engine (mines turbo though)with 150k on the clock, costs me £45 to fill it and normally get around 600 miles to the tank with mostly motorway driving at 70/75.
I must say my economy has dropped in the winter months as I ve been getting 550 ish to a tank instead of 600+ in Sep/Oct
Also I agree with you that some filling stations do offer better economy than others- I only got 500 to the tank from Sainsburys whereas 550-600 from Morrisons.
I would suggest getting the injectors checked though as they could be worn.
Regards
Martin
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I have a 1995 DT (170K on the clock)
I get about 400-450mile to a tank, but I only do shuttle runs 10miles to work, 10mile back, and the occasional run to the out laws (60 mile round trip)
However, If I do get on the motorway for a long run she's good for 500-550 no worries.
I keep reading about winter diesel, basically in from Oct to Mar (i think) the fuel suppliers add addition additives to prevent the fuel from waxing, this does reduce performance slightly, it is the nature of the beast, but I personally can hardly tell as I run my DT with the pump set slightly above standard.
laters
H
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Miles to the tank: I have a 200k '95 1.9TD Xantia, so I've the suspension pump to run & the turbo. I mainly do motorway miles commuting from Oxford to Solihull at about 70mph. I expect to get 600-650 miles (65 litre tank). If I try hard, I can get it to top 700 (although this was in the summer)
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A quick update on mine , The tank only had a gallon and half, maybe 2 in there from the last 4 months so I got a gerry can (gallon) of fresh from the local filling station. Chucked that in along with some redex diesel treatment. Started her up and give a good old rev, kicked some nice smoke out but nothing strange there @20psi boost with fuel to match hehehehe.
Anyway, I let her run for a while to bring all the stagnant fuel out of the lines and start using the stagnant/fresh mix. She's definatley starting easier but still not as good as she used to 4 months back. Given the improvement from adding one gallon I'm going to try and just leave her run as much as possible whilst doing other jobs on her. Hopefully it will run dry and then I will get a nice fresh tank load. She should be coming out to play soon anyway, not much left to do then its off for test then tax.
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It may not be such a good idea to run your tank dry.
Any water or 'gunge' in the bottom of the tank will be sucked-in or you may have subsequent problems with air in the fuel system.
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