When I pull up the manual for my VIN on knowyourvw.com the fuelling section specifically states to stop fuelling at the first pump stop to leave proper head space for fuel expansion during events such as temperature increases.
It doesn't make any clarification for gas vs diesel.
Despite using my vin to pull up this manual, there are references to all options and engines available.
Some discussion about it:
http://www.thedieselpageforums.com/tdpforum/showthread.php?t=33686
http://forums.tdiclub.com/showthread.php?t=62886
Yes, the manual say don't do it.
It's obviously your choice as it's your car.
Manual states:
- The fuel tank is full when the automatic filler nozzle pump switches off the first time => See warning.
- Do not try and add fuel after the pump stops! Topping off the tank in this way may fill the expansion space that the tank needs and cause fuel to overflow, for example, if it gets warmer outside.
=> Warning: Spilled fuel can cause fires, explosions, burns, and other severe injuries.
- Always stop refueling once the pump nozzle switches off so that the tank does not overflow.
So let's discuss these.
First as mentioned, Diesel cars don't have a vapor recovery system to ruin. If you overflow your modern gasoline burner, it could overflow and saturate this system.
Second, the reason we don't have a vapor recovery system is due to the fact that diesel doesn't evaporate as fast as gasoline. This vaporizing can cause pressure inside the tank.
Third, no matter how hard you try, you are unlikely going to be able to fill the tank to 100% capacity. Therefore there will be some room for expansion if needed. Plus, the tank is not inflexible, it will expand a little if needed.
Fourth, Diesel foams a lot and will cause the pump nozzle to stop much sooner as compared to gas.
Fifth, if you can't determine when the nozzle stopped, you would need to use the same pump at the same flow rate to attempt to get the same reading every time. If you fill until you see the fuel in the filler neck, you don't need to be at the same pump and same pump speed to know you are full. There is still the pump accuracy to account for, but you get the idea.
Sixth, I don't have a fuel station at my house, therefore, I drive it after putting fuel in, thus consuming some fuel and creating room for expansion.
Seventh, one reason is to prevent spills, I am smart enough not to overflow the tank when filling, but it does require more effort and attention.
Eighth, diesel expands slightly less due to temperature as compared to gasoline.
For these reasons, I top it off.
Traffic light out and lots of cars. Then get my son and went to eat and then to drop him back off. Drove the 90 miles home from there fighting some rush hour traffic getting out of Columbus. I was sweating as I really wanted to get to your level of FE.
