Diesel and Gasoline: What's the difference?

If you’re looking to get a new vehicle one of the first things that you should look at is the type of fuel that you want your vehicle to run on. Vehicles these days run on two types of fuel: either diesel or gasoline. You can find both types of fuel at any gas station that you go to, though some may have special pumps just for diesel while others may just lack a diesel hook-up altogether. It’s all dependent on the gas station. At a glance, these two might look similar but they are actually quite different.

The price difference between these two fuel types is also a big factor. While diesel fuel is often seen as being the more expensive, gasoline can also get up in price such as when gas prices are affected by international trade. 

Diesel

Though minute there are differences between diesel and gasoline fuel. Diesel fuel is what is called a slow burner fuel. It is called this because it has a much slower burn time than gasoline and requires a lot of oxygen to cause a reaction. Most, if not all, diesel engines will need a compression ratio of 20:1 to make the air hot enough so that it will ignite.  Any unburnt diesel fuel is pushed out of the engine, which causes the black smoke look that is often associated with diesel engines. 

Diesel fuel is also self-lubricating. This means that as the fuel burns it will lubricate the parts that it runs through, making it harder for them to stick together and cause fewer issues in the large tanks. This is vital for the types of vehicles that diesel engines are often found in, such as big trucks or heavy machinery. At roughly -20 to -30 degrees diesel fuel will coagulate and turn into a gel, whereas gasoline does not suffer from ‘freezing’. 

Jet fuel is a type of diesel, as it burns slow like diesel but it is safer as it does not explode.

Gasoline

Gasoline is more refined than diesel, being comprised of multiple carbon molecules that range in size. When combusted the gasoline is combined with clean air, which in turn make a vapor that is used to help ignite the gasoline and bring power to the vehicle. While this is happening the much large molecules are harder to burn, so it is estimated that only about 80% of fuel is burned the first time. Because of how the fuel burns this is the reason that gasoline engines are predominately found in vehicles that have small engines and need small horse-powers.

Unlike diesel, gasoline is not self-lubricating, which causes the metal parts to rub together. That is why you see people opt for using the higher grade, more expensive gasoline in their cars, especially if they are going on a long trip. This will minimize the wear on a vehicle while you travel. Gasoline will also evaporate quickly, while diesel will not. 

Frequently Asked Questions