I went with the oil drilling rig approach, mainly because I couldn't find any oil Wells nearby
its working out well for me, 8buckets of nitro diesel gives me a bit over 240 buckets of raw oil, which with some basic processing will net me 300.buckets of nitro diesel which is for me at my current stage, a metric beepton of EU. 500k+ EU per bucket of nitro diesel, so that's on the plus side of 150 million EU
of course there is spent some additional EU on processing the oil, but that is a rather insignificant amount. even more so when my oil processing setup is still powered by steam, so I just grab a couple drums of lava now and then and it calast to process many drums of raw oil into nitro
BUT if you are very early in the steel chapter, I belive the oil rig will be close to unrealistic, especially as you are (presumably) new to Gregtech.
but as you can see from my simple math above, the amount of EU for a drum of nitro diesel, is huge, and if a spring like Pyure mentions, can fill several of not dozens of drums, then that will last you far longer than MV and probably HV stage
edit: all. the talk of cracking and distilling, ignore the cracking part for a long while, you do t have the machinery and can't make it either for a while yet.
distilling is needed, but it's relatively simple as you can't make the larger multiblock distilling towers yet either, so a basic distillery will be plenty good
(you lose out on a lot of by products as well as you have less efficient distilling with the non tower distillery, but it's still a huge gain in EU)