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.
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.