I can never keep the names, let alone the initials, of the three oils
straight.  Thus some time ago I looked it up on the internet.  Here is what
I found and copied:

Holy Oil-There are three special oils used for various blessings and
celebrations.  They are blessed once a year by the Bishop at the Mass of
Chrism, usually celebrated in our diocese on Holy Thursday.  Each oil is
blessed with a special prayer, depending on what the oil is used for.

· Oil of the Catechumens is used for the first anointing during the
celebration of infant baptism.  It seen as a sacramental that wards off
evil.  On the container which holds the oil are the letters OC (Oleum
Catechumenorum) or OS (Oleum Sanctum) to indicate Oil of Catechumens.

· Oil of Sacred (or holy) Chrism is used for the main blessing with oil
during the baptism of a child.  (The first blessing with oil, using the Oil
of Catechumens is optional.).  In additional, the Oil of Sacred Chrism is
used when a bishop administers the Sacrament of Confirmation.  It is also
used by the Bishop when a man is ordained to the priesthood.  This oil has a
fragrance to it, which is produced by adding a bit of perfume [often Balsam]
at the time of the Bishop's blessing.  This oil is seen as the sacramental
sign of the gift of the Holy Spirit.  [These three sacraments confer
character.]  On the container which holds the oil are the letters SC
(Sanctum Chrisma) to indicate the Oil of Sacred Chrism.

· Oil of the Sick.  This oil is a mixture of the first two oils.  It is
blessed with a special prayer of healing, and is used for the Sacrament of
the Sick.  On the container which holds the oil are the letters OI (Oleum
Infirmorum) to indicate Oil of the Sick/Infirm.

Added to the history Charles+ sent, maybe this helps.

John+


----- Original Message -----
From: <chasrscott@...>
To: <faithandlife@...>
Sent: Monday, December 29, 2003 2:41 PM
Subject: [FaithandLife] Holy Oils


>
> Fr. Vanderbijl wrote:
> <snip>
> BTW, would one of the more learned fathers care to explain the three
> different oils used in the church, their origin and reasons, etc?  I
believe that the oils are blessed by the Bishop at an anual service <snip>
> Do y'all do the service mention above?  I've never heard of it in the
> REC...maybe in the mid-west...Dr. D.+?
>
> Fr. Vanderbijl