A cheat to get heaps of oil credit in KKND
Begin a level and then save the game.
Use a hex editor - I use XTGOLD -
In XTGOLD highlight the saved file and then press V for view, H for Hex, E for edit. After you have edited the hex press enter, Esc and quit XTGOLD. Now go back to KKND and restart your saved game.
In the Survivors levels the first line of your hex will look something like this:-
000000 0100 0000 0000 0000 0000 0000 0000 0000
Regardless of the numbers that may be in your saved game change this to:
000000 0100 0000 0000 0000 F301 F301 F301 0000
This will give you over 32 million oil credits.
In the Mutants levels your hex will look something like this:-
000000 0200 0000 0000 0000 0000 0000 0000 0000
Change this to:
000000 0200 0000 0000 0000 0000 FFFF FFFF FFFF
This will give you a negative oil figure with the result that you will never run out of oil credits.