What day of the week should you fill up your fuel tank?

By Russ and Tiña De Maris

When you live fulltime in your home-on-wheels, it may be possible to pick the day you fill up with fuel. But does it matter? Will it save you money? While it’s not always possible to pick a specific day of the week to fill up the old motorhome, if you can, you just may save yourself a few bucks reports the fuel-price watcher, GasBuddy.com.

The company took three years of price data, crunched it, and came up with a rule-of-thumb for buyers across the U.S.: Fill up your tank on Monday. If you really want to spend the most money, then put off your fill-up until Thursday, as on average, across the country the highest prices occur then.

Actual “best” days depend partly on where you are in the nation, but as a rule, Monday is the best. In essence, though, no matter where you are, the earlier in the work week, the better the prices will be. What accounts for the fluctuation in fuel prices? GasBuddy officials think it has much to do with the federal Energy Information Administration report that’s released every Wednesday. Fuel prices may swing up, depending on what information the report shows, and Thursday is the knee-jerk reaction day if prices will climb. Come the weekend, when commodity traders are “off work,” then prices tend to stay where they are.

Essentially, Monday is the least expensive day to fill up, followed by Sunday. Other days are good when “topping off” the tank — those are Tuesdays and Fridays. And the best days to avoid at the fuel pump altogether are Thursdays and Saturdays.

If the entire country flooded to gas stations to fill up on Thursday, each week for a year, by the end of the year the collective purchases would amount to $1.1 billion dollars more in fuel costs than if everyone tanked up on Monday.

GasBuddy.com produces a free app for both Apple and Android devices that allows users to price shop for fuel (both gasoline and diesel) anywhere in the country. By their reckoning, app users can save an average of $325 per year by shopping around. And with fuel prices expected to rise over summer, punching a few buttons on your tablet before punching your credit card in the slot at the fuel station may just save you a bit of change.