When is it ok to leave LO alone in the car?

babywinks

Ok so I pay at the pump when getting gas so obviously then its ok, but what about if you have to run inside to pay? And if that is ok what about grabbing a drink? Also have you had to bring LO into a regular public restroom i.e. not the nice family ones? How does that work? If you can't tell LO and I don't go out much just the two of us!