Summer/winter gas

[forgotten_aria]

Has anyone ever had a problem with a car (or heard of a direct friend) that didn't get driven much that had the wrong season's gas in it? I've heard that in extreme cases it can cause starting problems, but perhaps the Boston formulas aren't that extreme?

Comments

[alphacygni]

I've never heard of this, actually. Gas has seasonal variations? But my car isn't driven much, and has probably been in this situation on the seasonal borders at least once, and I've never had a problem with it starting.

[forgotten-aria.livejournal.com]

From wikipedia: In cold climates, too little volatility results in cars failing to start. In hot climates, excessive volatility results in what is known as "vapour lock" where combustion fails to occur, because the liquid fuel has changed to a gaseous fuel in the fuel lines.

In the United States, volatility is regulated in large urban centers to reduce the emission of unburned hydrocarbons. In large cities, so-called reformulated gasoline that is less prone to evaporation, among other properties, is required. In Australia summer petrol volatility limits are set by State Governments and vary between capital cities. Most countries simply have a summer, winter and perhaps intermediate limit.

[jered]

What she said. Basically, in the winter they add up to 10% ethanol to the fuel to add oxygen (increasing combustion efficiency) and increase volatility. This also has the effect of reducing mileage -- yet strangely you don't get a discount in the winter for the fact that they're given you less petroleum...

And to answer the original question, maskin77 says that the winter gas in summer vapor lock issue does occur, but he hasn't heard of it happening with a modern car.