by The Capital Institute of Consumer Expertise decided to check gas station networks for the presence of authentic winter diesel fuel and collected samples from a dozen popular networks. It discovered which ones meet the long-unadopted Euro-6 standards and which ones adhere to the long-discarded Euro-4. 
For a long time, official importers refused to bring diesel cars into Ukraine – the quality of domestic diesel fuel was too unstable. Especially during the winter period – fuel filters with common rail injection systems would instantly clog up with summer diesel fuel. This was repeatedly confirmed by our tests – finding decent “winter” diesel turned into a real quest.
Dealers could be understood – a single fueling with such diesel could disable the high-pressure fuel pump, sometimes accounting for more than half the diesel vehicle’s cost. 
Diesel Dozen
We tried to conduct the most comprehensive sampling possible, selecting samples from discount and globally known networks, newcomers, and veterans of the market. Certified laboratories received samples of heavy fuel from capital gas stations WOG, OKKO, KLO, Amic, ANP, Chipo, Glusco, Marshal, Motto, Shell, Sunoil, and BRSN-Nafta. Apart from commercial grades, we also analyzed branded blends enriched with various additives. The tests were conducted based on five primary parameters regulated by GOST 7688:2015: cold filter plugging point, water content, cetane index, sulfur content, and density.
Degree of “Solidification”
The main diesel fuel issue concerning drivers is its frost resistance. Too fresh in memory are the times when fuel pipelines had to be thawed with blowtorches. The aforementioned industry standard divides fuel into summer and winter based on the cold filter plugging point. In the former case, the critical mobility threshold should only occur when reaching -5 °C, in the latter, already at -20 °C. This standard also regulates water content in fuel – no more than 0.02%.
Otherwise, at sub-zero temperatures, ice crystals will clog fuel filters and pipelines as effectively as paraffin diesel fuel. Although none of the expert samples contained any water (indicating competent logistics and proper fuel storage), only eight samples can be considered truly winter-grade. Encouragingly, “heavy fuel” from WOG and OKKO only thickened at -30 °C, while two other samples (Chipo and Motto) were just a degree shy from an “arctic” mark. 
Number and Index
An equally important parameter for diesel fuel is the cetane index, which reflects the influence of additives improving its cetane number. The higher the index, the easier it is for the engine to start in cold weather and the more stable it runs.
This time, no one had issues overcoming the minimum threshold of 46 units. Again, the greatest “margin of safety” was noted in samples from WOG and OKKO, with good results also shown by samples from BRSN-Nafta and Chipo. 
Energy Density
While there can never be enough cetane, diesel fuel’s density (the energy it releases) must remain within strict limits. According to GOST 7688:2015, at a temperature of 15°C, the density should remain within 820–845 kg/m3. Again, all twelve samples strictly adhere to the prescribed corridor.
Risk Group
The main environmental parameter of diesel fuel is excess sulfur. When burned, sulfuric and sulfurous acid concentrates not only coke up catalytic converters and fuel equipment but also irritate human mucous membranes. Previously, high sulfur content was tolerated due to its fairly good lubricating properties, but with the invention of more advanced and eco-safe lubricating additives, sulfur is being phased out. Each new Euro norm mandates a reduction: the Euro-3 adopted in 1999 allowed for 350 ppm (mg/kg) of sulfur in 1 kg, while the Euro-5 introduced ten years later (and currently enforced in Ukraine) limits it to 10 ppm. Although all sampled fuels met the standard, there’s a notable variation among them by this parameter.
The leading four (OKKO, WOG, Chipo, Motto) maintained sulfur at 3-4 mg/kg, while Glusco and Marshall samples barely met the mark at 10 mg/kg.
Diesel Drivers Can Rest Easy This Winter
According to the tests, the quality of diesel at domestic gas stations is higher than ever, and in some respects, it even meets the postponed Euro-6 which was deferred for another year. Most importantly, no one allows themselves to sell “summer” diesel during cold periods, a practice that had been noticed multiple times before. Alexander Babenko
