Oil Power Plants cost $7,000 and no resources to build. Each turn they use 0.1 Oil per 100 Infrastructure that they're powering and $150. This adds up to 1.2 Oil per 100 Infrastructure and $1,800 a day.
Oil Power Plants add 6 points to your Pollution Index.
Each Oil Power Plant can only power up to 500 Infrastructure levels. Once a city reaches 500.01 or greater Infrastructure it requires at last 2 Oil Power Plants to stay powered.
To fuel a power plant, you must have the applicable resource available in your nation's inventory. For example, in a city with 1 Oil Power Plant and 500 Infrastructure, you'd need at least 0.5 Oil on hand for your city to have power. Your power plants do not use the Oil you produce every turn; instead they rely on what's available in your nation currently.