Has anyone seen these new Ocean Oil Field biomes? They were added to the mc 1.5.2 builds of BuildCraft, they seem to provide a great source of BuildCraft oil, which used to be somewhat annoying to obtain at times.
The large "oil towers" have huge caves filled with oil under them, under the ocean floor. The smaller ones also have some smaller caves under them.
I'm not sure if this was the case before, but oil seems to be slightly transparent now as well, but not nearly as much as water.