Will Gasoline and Diesel Separate When Mixed Together?

[StAmir]

Gasoline and diesel will not separate when mixed together. Here are the detailed explanations: 1. Gasoline: The specific gravity of gasoline ranges from 0.71 to 0.77. The higher the density, the larger the aromatic hydrocarbon volume. The standard reference for marketable finished gasoline is 0.755kg/L, and its price fluctuates based on its actual density. Due to its low density, gasoline floats on water, making it generally impossible to extinguish with water unless used as a fine mist. High-quality gasoline should remain stable for six months of use. However, since gasoline is a mixture rather than a single compound, it will gradually degrade over time due to the separation of its components. 2. Diesel: Diesel is primarily blended from diesel fractions produced through processes such as crude oil distillation, catalytic cracking, thermal cracking, hydrocracking, and petroleum coking. It can also be obtained through direct distillation or cracking processes from crude oil or shale oil. Depending on the properties of the crude oil, there are paraffinic diesel, naphthenic diesel, and naphthenic-aromatic diesel, among others. The calorific value of diesel is 3.3*10^7J/L.

[HarleyLynn]

From a car mechanic's perspective: Gasoline and diesel will definitely separate when mixed. I've opened fuel tanks many times and seen it - gasoline has a density around 0.72, while diesel is 0.83 or higher. The density difference makes them layer like oil on water. Last year, a Tiguan was misfueled, and when we drained it, you could clearly see two distinct layers - the lower diesel layer was dark yellow and cloudy, while the upper gasoline layer was clear and transparent. The worst part is that the fuel pump will draw the bottom diesel layer first, which can directly clog the injectors and fuel pump. The repair cost over 8,000 yuan. A warning to all drivers: if you mix fuels, never start the engine - immediately call a professional to drain the fuel system, or you'll destroy the engine.

[LeAsher]

From a chemistry teacher's perspective: These two oils are fundamentally different. Gasoline mainly contains C5-C12 hydrocarbons, while diesel consists of C10-C20 long-chain alkanes. The difference in molecular structure prevents them from being mutually soluble. Experiments show that the mixed liquid separates into layers after standing for 30 minutes: the lighter gasoline occupies 90% of the upper layer, while the lower layer is viscous diesel. This follows the same principle as the separation of water and oil, due to significant differences in surface tension. When mixed, the high compression ratio of diesel engines can cause knocking, while gasoline engines won't ignite at all due to the difference in ignition points. In one student experiment, burning the mixed fuel also produced a large amount of carbon deposits.

[StColin]

Used car dealer experience: Witnessed heartbreaking cases when purchasing vehicles. Last year, a diesel pickup truck was mistakenly filled with 92-octane gasoline and stalled after just 10 kilometers. Inspection revealed gelatinous sediment at the bottom of the fuel tank, with the fuel filter clogged like it was coated with asphalt. Gasoline's strong solvent properties wash out all carbon deposits from tank corners, while diesel's lubricity deteriorates. Layered fuel entering the engine is like drinking the sediment at the bottom of a cocktail—extremely damaging to piston rings. Fixing such vehicles requires complete fuel system disassembly, costing over three times more than regular maintenance.