Diesel fuel was on heavy discount at a rural Wisconsin convenience store — just 59 cents a gallon.

That is, until the owner discovered he had left off the other $3 while changing the price in his computer.

Mohinder Singh estimates 50 to 75 customers took advantage of the mistake at his Lyons Shell Plaza last weekend, costing him more than $4,000.

He says he changed the price about noon Saturday, and it stayed at 59 cents until he arrived at 7 a.m. Sunday and saw a warning light indicating the diesel tank had only 200 gallons left.

Eighteen-year-old Jordan Koster knew something was wrong when he filled his pickup's 30-gallon tank for only $10. He told his father, and his father advised him to make things right.

The teen stopped Monday and paid the full amount.