FUEL FOR THOUGHT
Story and photos by Howard Shanks
WINTER DIESEL D E N I A L P X E
Is frozen diesel impossible in the Antipodes? Think again… Here’s everything you need to
know about how cold weather affects diesel.
H
ere in the Antipodes, winter conditions are incredibly mild compared with places like Alaska, home of the Ice Road Truckers, where trucks are expected to operate well below sub-zero temperatures. But one of the biggest challenges ice road truckers face is preventing fuel from freezing. Surprisingly, in some parts of New Zealand and Australia, trucking operators can face similar challenges in severe winter conditions. In certain
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areas, diesel fuel may get cold enough for the wax it contains to start solidifying, sometimes known as frozen fuel. All diesel fuels contain wax, a natural component of crude oil. One benefit of the wax is it boosts the fuel’s ignition quality. Nevertheless, suppose the cold weather causes enough wax to solidify (or crystallise)? In that case, the fuel lines, filters and strainers in a diesel engine may become blocked and make it difficult or impossible to start and operate the truck. Hence, the phenomenon known as July 2022
‘waxing’ the fuel. Not all diesel fuel is the same. Fuel companies make dedicated ‘winter diesel’ blends, specially formulated with lower cloud points than regular diesel, to prevent waxing from happening. The cloud point refers to the temperature below which wax in diesel will begin to go cloudy and solidify. The cloud point for diesel varies seasonally, with diesel manufacturers producing diesel with a cloud point up to 4°C lower during the winter months. However, this temperature still may not be low enough to prevent waxing from occurring in cold alpine regions. To better combat coldrelated fuel problems, it’s
worth investigating what happens to fuel at low temperatures. Firstly, let’s clarify some of the terms used when discussing temperature’s impact on diesel fuel. Waxing: As we touched on earlier, solidfiying wax – with fuel literally turning to jelly – is relatively rare. Waxing occurs when the paraffin wax in diesel solidifies because of a reduction in temperature. The fuel temperature generally has to stay below -3°C for 48 to 72 hours. The paraffin wax in diesel solidifies when subjected to extended cold temperatures below freezing, giving the fuel a cloudy appearance. Even so, fuel can begin to cloud at temperatures as high as 0°C, but it will continue flowing. Fuel must remain very cold for long periods before it will actually wax up. It’s not uncommon to hear long-distance drivers from northern regions complain about their fuel waxing up when they have to spend a night or two in southern areas during winter. However, that’s probably not the actual problem: the more likely
