Diesel Fuel Gelling in Cold Weather

Diesel fuel contains wax-like hydrocarbons. As temperature falls, wax crystals form and grow. Enough wax buildup restricts fuel flow through filters and lines, which creates cold-weather operating problems.

Why diesel gels and gasoline does not

Gasoline stays liquid at low temperatures. Diesel contains paraffin wax molecules that solidify as temperatures fall. When enough wax forms, fuel stops flowing through filters and lines.

Cloud point, CFPP, and pour point

Cloud point is the temperature where wax crystals first appear. Cold filter plugging point estimates when wax starts clogging a filter. Pour point is the lowest temperature where fuel still flows. Each test describes a different stage of the same cooling process.

What gelling looks like in practice

An engine that cranks but will not start, long crank times on cold mornings, or a filter full of waxy material all point toward fuel-flow problems caused by cold.

Related product guide

Xp3 Diesel Winter Extreme is an MPG cold-weather diesel treatment. MPG publishes its own temperature performance numbers on official product information. ESX keeps those numbers attributed to MPG rather than restating them as independent findings.