Sun light effects on gasoline?

[Birel99]

Hi,
What effect does sunlight or any UV light have on the condition of Gasoline?

does it effect the performance of the fuel?

Thanks!

[Mikey_s]

Hmmm, a strange question. I can offer a couple of general answers, but why would you want to know this?

Firstly gasoline is seldom exposed to sunlight. The first and most obvious effects would be heating. Gasoline is extremely volatile (flash point is far below zero typically). Therefore if it was in an open container it would start to evaporate and the lightest fractions would go first. These can be as low as 3-4 carbon chains and the molecular weight distribution would be affected.
In a closed conatiner the rpessure would increase dramatically as the vapour pressure of the lighter molecules increased above their boiling point.

In a transparent container, over a prolonged period it is feasible that UV light might cause some cross-linking and lead to the formation of some 'gummy' substances that would atart to foul filters and lead to carbonaceous build up on the engine internals.

It's tricky to be mre specific without more detail about the conditions.

On a practical basis the product almost never 'sees' daylight.

[Birel99]

My reason for asking is in karting, the gas tank is made of a plastic that may only stop maybe 60% of sunlight. Thanks for the help!

[casper]

During, the 1 to 2 hour race duration, sunlight will have no effect on fuel quality. If exposed too long in the sun like 3 months or 6, the light ends will evaporate leaving a gasoline with heavier hydrocarbons.

All gasoline producer (except maybe Russia) follow the very strict gasoline composition limits set by the American Society for Testing and Materials (ASTM). Gum formation tendency of gasoline is determined by the Existent Gum Test, with a max limit of 4 mg/100 mL. Typical gum is 1 mg. The refining process removes all gum-forming hydrocarbons and addition of fuel additives further improve fuel stability.

Gasoline composition however differ between each summer and winter seasons.
From http://www.faqs.org/faqs/autos/gasoline-faq/part1/

"Volatility affects the driveability of a vehicle so much so that fuel for mid-summer Arizona would be difficult to use in mid-winter Alaska. The US is divided into zones, according to altitude and seasonal temperatures, and the fuel volatility is adjusted accordingly. Incorrect fuel may result in difficult starting in cold weather, carburettor icing, vapor lock in hot weather, and crankcase oil dilution."