Gasoline prices spike on some days and drift down on others, and after studying the trends over a number of years,'s Pat DeHaan finds a pattern.

The Senior Petroleum Analyst told WOOD TV the weekend has the most number of days that you have a chance to fill up at less than the weekly average.

In the past two years, DeHaan said Fridays are the cheapest gas days in West Michigan. 

He notes that is good from a traveling/tourism vantage, since those are the days you are likely to buy more gallons.

Oddly enough, after making this generalization, he notices that gasoline prices are expected to spike today.  Thursday is not a weekend, but says it's "approaching the weekend."

If pump prices do jump today, DeHaan said, "it would be the 18th time that prices have spiked up in 2014".