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Wintertime motor maintenance

Picture this: you’re in a rush to a meeting, should have left the house 15 minutes ago, but spilled the coffee twice and couldn’t find your keys, as usual. Finally, you’ve tossed your stuff in the car, gotten comfortable at the steering wheel, buckled up and noticed, that with a little luck, you might actually still be on time. A victorious smile adorning your face, you turn the key in the ignition and… instead of the faithfully familiar sound of a rapidly starting engine, the car lets out a whine and goes quiet. You try it once, twice, fifteen times. Nothing. All but crushed, you call yourself a taxi, and then your boss to let him know you’ll be late. Putting your coat on, you step out of the car and go freeze out in front of the house.

Winter Fuels

Sound familiar? Unfortunately, an engine that won’t start is all too common in the winter time. Luckily, there are measures you can take to prevent this unpleasant situation.

One of these is to use the winter fuel Verva Diesel. In comparison to petrol, diesel is more demanding, especially during winter. The most common problems are cold starts at sub-zero temperatures, or potential diesel solidification, also referred to as “freezing.”

The problem lies in diesel’s overall chemical composition, which consists of a mix of hydrocarbons with various solidifying temperatures. The main issue comes from paraffin wax, with which it’s important to consider two parameters.

The first one is temperature, at which the first solid paraffin crystals start being expelled. This temperature, referred to as Cloud Point, moves around -6°C to -8°C. This temperature, which the ČS EN 590 + A1 does not provide, is given by technology in the refinery, and no additive can lower it. With another drop in temperature these initially small paraffin crystals will form into large, leaf-sized particles that can easily clog a fuel filter even in much lower temperatures than the filtration caliber, i.g. even in -12°C.

The second important parameter is the Cold Filter Plugging Point, which gives the temperature at which diesel no longer passes through the sifter. The ČSN EN 590 + A1 calls for -20°C temperature for CFPP class F winter fuel filterability ( acceptable  measuring deviation allows for temperature up to -17 °C) in the time period between 16th of November until the end of February.

The reality is different

In practice, the actual operational temperature is different, which is caused by the difference in laboratory conditions of CFPP tests with realistic motor motion during standard operation. Varied fuel system constructions in individual vehicles have diverse sensitivity to CFPP as well as the aggregate motor function in frosty weather. This means that the behavior of various types of vehicles will be different, even when they are filled up with the same kind of diesel.

Another reason behind frequent engine starting difficulties is the presence of the wrong type of diesel in the fuel tank, respectively a supply of transitional or even summer diesel. This diesel’s winter parameters won’t improve, even with added additives or by mixing it with winter quality fuel.

Poor motor maintenance

Have we, drivers, won the battle with good motor diesel filterability? Unfortunately not. An important influencing factor for good combustion engine function in wintertime is total vehicle maintenance and upkeep, a lack of which is typically implicated in all engine starting issues. Whether it is an insufficiently charged battery, not capable of providing enough energy for spark plugs to warm up ignition spaces, within which the diesel ignites, or neglected fuel line maintenance.

Worsened filterability is most often caused by a fuel filter that has been sullied by water, which can get into the fuel tank, for instance, from air humidity (such as in the case of frequent refueling, where the gas cap is being opened very often, a poorly sealed gas cap, and so on) or in the case of an incompletely filled fuel tank. In this case, tiny droplets of water will form from air humidity and a minimal amount of eliminated paraffins will pack onto them, which can easily clog the fuel filter.

The minimum amount of eliminated paraffins can also pack onto mechanical dirt, which may already be located in the fuel tank or on the fuel filter. For that reason, it is best to have a clean fuel tank and to regularly change the fuel filter, ideally before winter and other time periods with temperatures temperatures.


To make this winter a little easier on yourself, follow these basic principles:

-        No water or mechanical grime in the fuel system. This means a clean fuel tank and a changed filter, ideally prior to winter season

-        Only winter fuel in the fuel tank. No transitional or summer fuel.

-        No long-term parking in severe frost and extremely freezing temperatures. If done, only with a full fuel tank (so as to prevent the settling of air humidity)

-        Sufficiently charged battery

By following these principles, you will mitigate winter time engine starting problems to the minimum. When using Verva Diesel, you will be able to start your engine without problems in temperatures up to -26°C.