mate if you cant syphon it i wouldnt be that worried, its only 2lt.
If you fill the tank to the top you wont have problem.
I have been in a car where the owner put a good 15lt in and we didnt notice any real difference, but that was not a common rail motor.
Like i said if you cant get it out easy just fill it to the brim, and when you get to a quarter top it up again.