Holy oil, also known as chrism oil, is typically used in holy orders. This oil is consecrated by a bishop and is used for anointing during sacraments such as baptism, confirmation, and holy orders in the Catholic Church. It is a mixture of olive oil and balsam, symbolizing the presence of the Holy Spirit.

There are three: Oil of Catechumens; oil of the sick; oil of chrism

In a way oil is a sgn of the holy spirit as it keeps thelamp burning.

Yes, "Holy Oil" should be capitalized when referring to it as a specific religious ceremonial substance.

It stands for Jesus Christ and the Holy Trinity.