Winter diesel info

[muddyboots]

Hi all

I recently sent a few questions about winter diesel to a well known fuel company, and (eventually) got a reply back.
I thought some might find this interesting, especially considering the temps we got down to in the UK last winter (think I saw -18ºc in Derbyshire, sure others saw lower than that).
Bear in mind this relates specifically to one brand; I have no idea if other brands are the same.

Regarding your technical questions for diesel, please find the answers below for your reference:

1) Does the formulation of regular diesel change during the winter months in the UK ?

There are different cold temperature requirements to be met for diesel between summer and winter.
For winter the requirements are -5degC cloud point max and -15degC CFPP(Cold Filter Plugging Point) max.
For summer the requirements are +3degC cloud point max and -5degC CFPP max.

2) If so, at what times of the year is the "winter" formulation supplied to forecourts ?

From 16th November to 15th March

3) What is the lowest temperature that diesel will remain useable during winter (ie before it starts to wax/freeze) ? Assuming my car is parked outside in an unsheltered spot overnight, and I usually start my journey around 6am.

Cold filter plugging point is the parameter used to measure the cold flow properties of diesel that is linked to engine operability.
For winter the CFPP max for the UK is -15degC and this doesn't mean for certain that the vehicle won't work if the temperature is less than 15degC, but it does mean that the risk of issues increases.


4) What is the likely effect on passenger car fuel economy, of the change in UK diesel formulation during winter ?

There are various factors that influence fuel economy including the type and condition of the vehicle, the way it is driven, weather conditions, road traffic conditions etc.

 

[cheshire cat]

cheers for that Muddy

 

[muddyboots]

cheers for that Muddy

You're still hanging round here as well then

 

[tdi_swedge]

Good bit of info here ! Thanks for sharing it

Ste

 

[derelyth]

Intriguing! Any chance of mentioning which well known company it is? Cheers

 

[jenk]

Cheers for posting and good to see they got back with a technical response. On the coldest day last winter (can't remember the temperature but it was mental) mine started real rough and then ran in limp mode, perhaps the diesel froze/thickened as it wasn't prept for that temperature?

 

[muddyboots]

Intriguing! Any chance of mentioning which well known company it is? Cheers

Well the disclaimers in the email I got suggest I should be careful about distributing the content.

So I won't say who it is, but it's a brand I'm happy to shell out that little bit extra on, compared to supermarket fuel.

 

[derelyth]

Well the disclaimers in the email I got suggest I should be careful about distributing the content.

So I won't say who it is, but it's a brand I'm happy to shell out that little bit extra on, compared to supermarket fuel.

Ah OK, not a problem cheers

 

[Swig]

I certainly saw -15 in Derbyshire. Didn't have a problem starting the engine (although >1 glow plug cycles helped). Keeping the windscreen clear was horrendous though.

 

[muddyboots]

The diesel geeks among us might like to know that - the above fuel company at least - are now supplying winter diesel, according to the response they gave me. So one might guess that most of the major brands are too.

Be interesting to see if there are any general patterns in MPG change taking place as a result - although it would be hard to know if it's related to fuel or to general dropping in temperatures...