Diesel also called petrodiesel in Technical Terms, is called High-Speed Diesel (HSD) which is also produced from the fractional distillation of crude oil between 200 °C and 400 °C resulting in a mixture of carbon chains and is composed of saturated hydrocarbons (primarily paraffin including n, iso, and cycloparaffins), and aromatic hydrocarbons (including naphthalenes and alkylbenzenes).

The principal measure of Diesel fuel quality is its cetane number.A higher cetane number indicates that the fuel ignites more readily when sprayed into hot compressed air.

Diesel engines do not use high-voltage spark ignition (spark plugs) burning the fuel in more air than is required for the chemical reaction. They thus use less fuel. Because they have high compression ratios and no throttle, diesel engines are more efficient than many spark-ignited engines. Engines running on diesel also provide more torque and are less likely to stall, as they are controlled by a mechanical or electronic governor.

Diesel-cars generally have a better fuel economy than equivalent gasoline cars. Their greater economy is due to the higher energy content per-litre of diesel fuel and the intrinsic efficiency of the diesel engine. However, the increased compression ratios mean there are increased emissions of oxides of nitrogen (NOx) from diesel engines which becomes the main drawback of diesel versus gasoline engines.

Diesel fuel is widely used in most types of transportation (Heavy commercial Vehicles, Buses), exclusively for the combustion engines of self-powered rail vehicles (locomotives and railcars), Tractors, Power Generation, Pump sets and in various other diesel engine driven applications.

A disadvantage of diesel as a vehicle fuel in cold climates, compared to gasoline or other petroleum-derived fuels, is that its viscosity increases quickly as the fuel's temperature decreases, turning into a non-flowing gel, at temperatures as high as -19 °C or -15 °C, which cannot be pumped by regular fuel pumps thus starting a diesel engine in very cold weather may pose considerable difficulties.

Since diesel engines do not require spark ignition, they can sustain operation as long as diesel fuel is supplied. Fuel is typically supplied via a fuel pump. If the pump breaks down in an "open" position, the supply of fuel will be unrestricted, and the engine will run away and risk terminal failure.

Sulfur in the fuel is oxidized during combustion, producing sulfur dioxide and sulfur trioxide. However, the process for lowering sulfur also reduces the lubricity of the fuel, meaning that additives must be put into the fuel to help lubricate fuel injectors.

In India, emission standards BS-VI have necessitated Oil Refineries to dramatically reduce the level of sulphur in Diesel in view of the National Auto Fuel Policy brought in force by the Govt. Of India. BIS has brought out the specification for “Diesel with 7 % Biodiesel”.

The High-Speed Diesel (HSD) marketed by our Corporation meets the Indian Standard IS 1460 : 2017 (6th Rev) governing the properties of diesel fuels.

Filter Paper Test (Petrol), Density Test (Petrol & Diesel), Quantity Check.