I start looking for gas when mine gets between 1/4 and 1/2 tank as I know mine is not reading right but mine really has a 1/2 tank when it shows 1/4 ,just overly cautious .My 74 Chevy truck that I drive daily the gage does not work at all so I keep 5 gals of gas in back all the time .I cant count how many times I have run out with it.