Diesel cars and Winter driving

[taz777]

My S80 is my first diesel car so I was wondering whether there's anything specific I should do or look out for as Winter approaches?

Or do modern diesels just work over Winter as petrol cars do, without any special maintenance?

[Dancake]

Don't let a diesel idle from cold. Keep your fuel tank brimmed as much as possible. Try to avoid short journeys as much as possible where the engine doesn't get up to operating temp.

[taz777]

Just out of interest, what's regarded as a short journey? Is it defined by distance or time?

There's no oil temperature gauge on most cars these days, only a coolant temperature gauge, and that doesn't necessarily tie in with the oil temperature.

The coolant gets to 'normal' temperature in just a few minutes, whereas the oil can take another 5-10 minutes over that in my experience based on previous cars that had oil temperature gauges.

[Scooser]

I avoid very short journeys full stop (winter or summer) and use the wifey's supermini for those.

Otherwise, I just get on with it in the winter, but try to give it 20 mins at 3000 rpm (3rd gear and 50 mph) does it as an insurance policy to keep my soot filter light off.

In 8 years I've had the soot filter light come on twice, despite plenty of town stop-start driving. A quick blast has cleared it.

[taz777]

I do a one-hour motorway journey at the weekends to keep the DPF happy. The advice about not letting the engine idle and keeping the fuel tank is new to me and I will adhere to it.

[Scooser]

Originally Posted by taz777

I do a one-hour motorway journey at the weekends to keep the DPF happy. The advice about not letting the engine idle and keeping the fuel tank is new to me and I will adhere to it.

Fuel tank is new on me. Over the last 8 years I've always run my V70 down to minimum (until it get to 35 miles to empty on the dash). Never had any issues.

What is the issue?

[Rooster]

There isn't really one if the car is used regularly especially on modern cars

[Dancake]

Keeping the fuel tank brinmed prevents the formation of condensation within the tank. It also serves to prevent the diesel from 'waxing' (or gelling). It isn't something that should cause any running issues in a modern diesel. The amount of water formation is very minimal.

However, my concern nowadays is the bio content of diesel. Diesel bug forms where water meets diesel, and can cause havoc with fuel systems. Diesel nowadays isn't the same as what it used to be. It has a higher biofuel concentration, though it also contains additives that prevent waxing. The biofuel content can cause the diesel fuel to turn into a gel like substance in cold temperatures. Once heated up, this gel remains in a gel like state. It doesn't merge with the rest of the fuel.

If your car has been regularly serviced (fuel filter replaced at or before the correct intervals) then you shouldn't have a problem. In my mind I am inclined to take the 'prevention is better than the cure' approach, hence the brimming of the fuel tank as often as possible in cold weather. It's perhaps being overvigilant to be honest.

[skyship007]

Originally Posted by taz777

I do a one-hour motorway journey at the weekends to keep the DPF happy. The advice about not letting the engine idle and keeping the fuel tank is new to me and I will adhere to it.

Short tripping is less of an issue in oil contamination terms than it used to be due to modern ECU and high pressure common rail fuel injection systems. With an older non ECU diesel that had a normal injection pump, the injector spray pattern was not very good at idle and that resulted in more fuel contamination than the more modern diesels, unless you have a DPF that uses the injectors to spray extra fuel to do a regen. The ones that use a seperate fluid tank and injector are far better.

The big issue with short tripping is when you don't get to do any motorway trips on a Sunday morning for at least a month. Not only will the Bio diesel contaminating the oil tend to build up, but the EGR will also get more deposits.

Changing the oil early does help to reduce the effects of blowby contamination, as does using an Xw40 rather than an 0w30.

Cheap supermarket winter diesel is only good for minus 15c, the good stuff from BP and Shell is good for minus 23c. If you get it wrong in a serious cold snap then try a major brand fuel additive that was designed to lower the gell point, otherwise the wax that is dissolved in the diesel drops out of solution and turns the fuel filter into a candle. The engine will start OK but then stall out later when enough wax has formed. For Artic operations you can fit a heated fuel filter unit or simply cook up the tank, like what the truckers sometimes do below minus 15c.

Always carry a spare fuel filter in the breakdown kit, just in case you get unlucky with a dirty fuel incident and make sure you know how to change it.

There is no need to brim off the fuel tank unless the car is not used for a long time (More than a month). I only half fuel my V40 each tank up, as that helps reduce the fuel consumption due to lower weight.

[Scooser]

By brimming the fuel tank continually you're also unnecessarily lugging around and extra 50 kg of diesel.