Originally Posted By: rationull
Is this really a problem?
Hard to say - after all, the fuel pumps are supposed to have filters on them.
I can say that I once asked a tanker driver what he was about to dump in order to avoid filling up my Golf while fresh fuel was going into the tank. He said that it was safe to use the diesel pumps as he had just started delivering gasoline but had not yet hooked up to the diesel compartment of the tanker.
The unspoken message being that
he would not fill a vehicle's tank while a tanker truck was delivering fuel.
While I think the risk of anything bad happening is small, there is still a
greater risk of filling up while the tanker truck is in the process of dumping fuel or shortly thereafter.
Originally Posted By: Bottom_Feeder
What exactly is risky about this?
Just to expand on rationull's post, underground tanks are not spotless, pristine examples of shining white-glove cleanliness. There's rust, scale, debris, dead pigeons, water, Jimmy Hoffa's skeleton and who knows what else down there, but most of that is resting gently at the bottom of the tank below the pump's standpipe. When the tanker truck delivers fuel, it's not gently lowered down and laid to rest with all the other fuel, it's literally dumped right into the tank which stirs up all the detritus mentioned above. So now you have a small (but growing) volume of fuel that has years of accumulated flotsam being churned around.
Some say that filling up while this is happening means you are far more likely to suck some of that muck up through the pump standpipe than if you fill up while a tanker isn't dumping fuel - and I have to agree. But how much of that would actually make it into you tank...
Life is all about managing risk. It's easy enough for me to keep on driving to the next station or fill up the next day, so I try to make a point to pass on by.