Processed crude oil and approximately 150 chemicals are added to the fuel cocktail known as gasoline. The mixture is refined and "brewed" to maintain specific characteristics like volatility. When gasoline ages, its composition degrades and it loses volatility. Using old gasoline can cause an engine to run rough.
As gasoline degrades, evaporation occurs and volatility is diminished, resulting in a less combustible product. Fuel that does not have an adequate volatility factor will not burn well in the engine and will cause problems like poor performance, difficulty or inability to start and rough idling.
Using up the old gas in a vehicle and topping the gas tank off with fresh gas is the best way to fix rough idle or other problems associated with old gasoline. If the vehicle will not start, syphoning out the old gas and replacing it with new gas is the best option.
It is important not to overexpose yourself to gas fumes when syphoning gasoline from a vehicle. Protecting your eyes with goggles and using a protective mask to avoid excessive inhalation of fumes is prudent. It is also essential to protect your skin from splashes of gas that can cause redness, swelling or rash.
