Why is it best to fuel up the car after 6pm?

Question

I've been seeing signs on the freeways to do this lately?

Answer 1

Key word "heat".

Gas is a liquid and has a fast evaporation rate. To pump gas during the day when it is hot out causes more evaporation of the gas being pumped. Hot days you see more fumes coming off the filler hole. In turn you get less gas in your tank and more fumes into the air.

This then puts more pollutants into the atmosphere causing smog which in turn causes hotter days. Same with mowing the lawn after dark, less un-mufflered exhaust fumes being cooked by the sun during the day.

Also why they say to water your lawn in the morning or night. Less evaporation of the water so more goes into the ground for the grass.

Answer 2

Sounds like the flex your power campaign in California. Using energy (in this case to run the gas pumps) after 6 PM helps keep the demand off of the peak usage on the power grids.

They promote this on the radio and billboards especially during the hot months of the year. So when you hear a PSA that says to flex your power, they are asking for people to not use their electricity between 10 am and 6 pm.

Answer 3

I'm just guessing here that it has something to do with supply and demand. Fleet vehicles, in other words trucks and semis, only can fuel before 6:00 if using a company card with restrictions. Maybe there will be a more consistant usage and the prices won't go as high.

Answer 4

It makes no difference to the car or you. The idea is that it will generally be cooler so there will be less evaporization while you fill up. Also the gas that does evaporate will not be so readily turned into smog and polution by the sun and other things.

Gasoline will evaporate at very low temperatures, usually as low as -45 degrees F. Different formulations will evaporate at slightly different temperatures.

Answer 5

It has to do with the ambient air temperature. Particularly in the south, where it is warmer, the early morning, and later evening times are the best to fill up your car.

The reason is that not as much of it turns to vapor and escapes.

Answer 6

I haven't seen those, so your answer is as good as my.

I think it has something to do with how much cool the gasoline and making your car run better.

Answer 7

i fuel up when i need gas, but after 6 pm, they've usually already raised the gas price if they are going to raise it that day.

Answer 8

sun is lower in the sky and doesn't convert the overflow vapor into smog

Answer 9

its probably better for the environment somehow