Curious what Book Of Oil actually feels like to play? Here's our full, no-fluff take. Built by Endorphina, it lands as a release with high variance and an RTP of 96.04%. Originally released in 2018, it has aged well. You get 15 paylines across 5 reels, all built around a book of theme. The maximum win sits at 50,000x, so there's serious upside on the table. Here's how it stacks up.
Written by Alex Crawford · Last updated: February 2026
This game, Book Of Oil, is the work of Endorphina, dressed up with a book of theme. It runs on a 5-reel grid running 15 paylines with a high-variance maths model, and 96.04% RTP.
Where Book Of Oil earns its keep is the feature set. Look out for scatter symbols that unlock free spins and extra bonus rounds. With high variance, this one is aimed at players who can ride out the swings for the top wins. All told, it's a solid entry in the Endorphina catalogue.
The RTP of 96.04% is right around the industry average of ~96%. This represents a fair return that's in line with what most modern slots offer.
High volatility means longer gaps between wins, but when wins do land, they can be significantly larger. A bigger bankroll and patience are recommended for this type of slot.
About 1 in 3 spins results in a win. This is a moderate hit frequency that balances win frequency with payout size.
Book Of Oil features scatter symbols that can trigger free spins rounds. Landing the required number of scatter symbols anywhere on the reels activates the free spins feature, giving you extra chances to win without additional bets. During free spins, special modifiers may apply to boost your winning potential.
3.0 / 5 — Good
Book Of Oil by Endorphina is a solid offering that delivers good entertainment value. The 96.04% RTP combined with high volatility creates a well-balanced gaming experience.