This was quite a readable (listenable) story for a novel set (and written) in the Twenties. Upton Sinclair was a prolific author who knew how to spin a tale, even while he was trying to expose the evils of capitalism. Sinclair's socialist beliefs are very much in evidence, but don't let that put you off -- he doesn't get up on a soapbox so much that it distracts from the plot (though it's obvious that the plot is there in order to push his agenda), and the setting, the situations, and the characters are all engaging and draw you into the roaring 20s oil boom in Southern California. Don't read this expecting it to be much like the movie loosely based on it, There Will Be Blood
. The movie adaptation was completely different and the story almost unrecognizable compared to the novel (though still good).
The weakness in Oil!
(besides Sinclair's socialist pot-stirring) is that it jumps around quite a bit. Most of it takes place in Southern California and focuses on the relationship between Bunny, the idealistic young heir to an oil fortune who becomes a "red sympathizer," and his father, the ruthless oilman who never stops doting on his son despite the fact that he keeps opposing everything his father stands for. But there is also Bunny's childhood friend Paul who comes back from serving overseas in Siberia to preach class struggle, his evangelical brother Eli, a Hollywood star, university student movements, rigged elections, spiritualists, and many other tangential subplots. They all connect somehow to the main plot, but if you like tightly-focused stories, this may be too distracting for you. I like stories with many different (not always related) threads, though, so I enjoyed it. A great historical novel despite the overt political preachiness.