GREENVILLE, N.C. (WNCT) — Are gas prices frustrating you? Have you joined a loyalty program, but it’s seemingly not paying off? If this is you, keep reading.

There is a science to stretching your dollars and getting more bang for your buck.

Weather can affect your gas tank and wallet. Gas molecules expand in heat, when temperatures rise in the middle of the day, your gas tank will expand. This is called thermal expansion.

Since the gas tank if physically bigger because of the gas molecules expanding, it will cost more money to fill up your tank. A way to combat this is to fill up on gas in the early morning or after the sun sets.

According to Gas Buddy, the best day of the week to save money at the pump is Monday. The worst day to get gas is Thursday.

The next time you’re looking to fill up, consider what day it is and the temperature.