Earlier this year, I received the following instructions on burning/maintaining an oil vigil lamp from the monks at the ROCOR Hermitage of the Holy Cross in West Virginia, upon asking. I had tried oil before, but didn't have much luck with it. It was too messy, among other things. I switched to beeswax votives made by the Hermitage's sister monastery for women. I wanted to try oil again, and so I emailed the monastery for instructions. Here they are!
Note, this uses the wick holder the monastery sells (as well as www.easternchristian.com), which are not the cork floats other used.
Vigil lamp Instructions:
Separate the four strands of cotton wicking.
Insert one strand into the wick holder, so that about 1/4 inch of wick is exposed above the shaft.
Bend the arms of the wick holder so that the shaft is about 1/2 inch below the top of the glass.
Fill the glass with oil up to the middle of the wick holder.
Pour some oil onto the exposed part of the wick.
Light the wick.
Glory to God!
To maintain your lamp by:
Pour oil on the flame to extinguish it, and then trim off the black part of the wick with a pair of small scissors. You can also pinch off the black part of the wick with a kleenex or tweezers.
The wick trimmings and any oil that you clean up from the lamp should be disposed of properly. i.e. We keep a burn bag and discard the kleenex and trimmings there. Then we burn the bag when it fills up and discard the ashes in a garden or somewhere they will not be walked on.
How often you trim your lamp is up to you. Maybe once a day- its a daily act of devotion we can show to our Lord and His Saints.
I do not recommend leaving your lamp unattended. i.e. If you are leaving your house for a while it is safest to put it out.
To clean the Wick Holder:
Remove the wick. You can hang it on the side of you Vigil Lamp.
Hold the Wick Holder over a metal pan or sink-- something that will not be damaged by hot sparks.
Hold a candle or lighter flame under the "sticky" shaft of the wick holder until the residue ignites.
When the residue is burned, run water over the Wick Holder to cool it down.
Shake the water out of the holder and re-insert the wick. You can wipe off the black carbon with a kleenex if you like.
Oil Recommendations:
Use a Light or Extra-Light Olive Oil. These have most of the olive "impurities" removed and make a cleaner,brighter burning oil. We use Bertolli's Classico in our Church. ExtraVirgin, Pure, Pomace, etc. all have more of the olive fruit in them and will not burn very clean. Do not use petroleum based lamp oils or paraffin candles, since they produce vapors/soot that is harmful for your icons. If you are trying to protect your icons, you might consider having a kiot made for them or having them framed in a traditional way.
Personal note: I keep my lit vigil lamp on my living room icon corner during the day when I am home. But when I go to bed, I move it into my bedroom and place it in front of the icons on top of my dresser. I like to be able to wake up in the middle of the night, as I often do, and see the light flickering on my icons. I've in several places that in pre-Revolutionary Russia many small children learned to not be afraid of the dark, when they would wake up scared, but see the icon lamp flickering on an icon of the Theotokos and Christ.
I hope this is helpful to you. Holy Cross Hermitage's website is www.holycross-hermitage.com