Americans have been getting hit hard at the pump with average gasoline prices in the United States up 50 cents per gallon since January. With many metro areas across the nation seeing the largest seasonal rise in prices since 2012, GasBuddy released a new study that found the best and worst days of the week to buy gas to maximize savings and avoid the lines during the busy summer travel season.

According to the study, Tuesday is the best day to buy gas in Oklahoma and Sunday is the worst day to buy gasoline.

GasBuddy analyzed gas price data from the period of January – March 2019 and found that the first day of the workweek offers the lowest average gas price in 30 states, making it the best day to fill-up. While Saturday is the worst day to buy gas in 16 states, Friday has the most expensive average price of any other day of the week.

“Finally, consumers have reason to be motivated about Monday since it offers the biggest savings on gasoline and little wait, if any, to fill up,” said Patrick DeHaan, head of petroleum analysis at GasBuddy. “As the week progresses and our excitement builds for the weekend, gas prices also tend to rise. The most expensive day to fill-up remains Friday when looking at averages, while 16 states saw Saturday have the highest average price. Sundays represented the third-worst day to fill up, bringing our study to a conclusion that weekends are the worst time to fill up. You might as well flush money down the toilet.”

Monday was also the best day to buy gas in 2018 and 2017, according to GasBuddy’s previous study.

What about waiting in line? GasBuddy also analyzed GasBuddy foot traffic data in the same timeframe and found that gas stations across the country are least busy on Sundays, followed by Mondays. Friday is the busiest day, with 5pm being the busiest time for gas stations nationwide.

“While filling up on a Sunday can save time, it doesn’t save money,” says DeHaan. “Our data shows that filling up on a Monday morning each week can collectively save drivers $2.1 billion and avoid the possibility of playing bumper cars at the pumps.”

Commuters looking to avoid the lines should fill-up on Monday or Tuesday between 7 – 10 a.m.