Oil gets in a swimming pool because someone grabbed a bucket of oil and threw it in the pool.

Vegetable oil is relatively to get out of a pool that is filled with water. The oil does not mix with water and will stay on the top layer. It can either be scooped out in a cup or the pool can be drained and refilled.

An oil pool account is a fund reserve maintained by the governments of many countries to protect citizens against fluctuations in oil prices. An example is the government of India.

That depends on the size of the pool is it a 2 stroke or a 4 stroke pool

Do you have a pool heater? The oil could be "white oil," a refined mineral oil. Indicates a problem with the heat exchanger. Your heater doesn't need to be running for this problem to occur.