To get past the petrol tanks that wont give you petrol, all you have to do is:

At the beggining of the 3rd level there is a rocket with fire coming out of it, run through the fire (you wont get hurt) and jump and hover over the platforms and into the gas to set the gas alight, and do that all the way to the nasty petrol pumps and the will explode.

ENJOY!!!!!!!