Petrol filler neck question

Hi All,

 I'm going to get the filler neck swapped and intend to do this myself. My question is- if I run the petrol down to about 1/5th a tank, will this be safe or will it pee petrol ou still? Is there an anti siphon flap that will stop it flooding out?

 Thanks in advance…..

 Mark.

Should be fine if you get down to about 1/5 full, esp as you jack up the car and the petrol slohes to the other side too.

Cheers bud,

 thought it best to check, a bit nerve wracking when you are staring at litres of inflamable liquid.
 The pipe takes some hammer on the outside doesn't it, mine was absolutely caked in mud at the top as well.

 Mark.