Do Essential Oils Expire?

Here is a chart showing the shelf life of certain essential oils:
from http://www.aromaticsinternational.com/shelf_life

Shelf Life

Shelf Life and Storage from the time of distillation:

It is impossible to say exactly what an essential oil shelf life will be. The storage conditions will vary and make a significant difference. If the essential oil has been received directly from the distiller shortly after distillation and the glass bottle is kept dark, full, closed, and cool, we can make some generalizations. Please note these are simply Aromatics Internationals opinions based on experience and an understanding of the chemistry of each oil.

Note that if an essential oil begins to appear cloudy, thicker, or if it smells more acidic, it has likely begun to oxidize.

Approximately 1-2 years from distillation:

Grapefruit - Citrus paradisi
Lemon - Citrus limon
Lime- Citrus aurantifolia
Mandarin - Citurs reticulata
Mastic - Pistacia lentiscus
Nutmeg - Myristica fragrans
Orange - Citrus sinensis 
Palo Santo - Bursera graveolens

Approximately 2-3 years from distillation:

Balsam Fir - Abies balsamea
Common Spruce - Picea Communis
Conifer Blend - Abies alba, Pinus nigra, Pinus wallichiana
Cypress - Cupressus sempervirens
Douglas Pine - Pseudotsuga menzies
Engleman Spruce - Picea engelmanii
Eucalyptus citriodora - Eucalyptus citriodora
Eucalyptus globulus - Eucalyptus globulus
Eucalyptus radiata - Eucalyptus radiata
Frankincense - Boswellia carterii
Galbanum - Ferula galbanum
Helichrysum - Helichrysum gymnocephalum
Helichrysum - Helichrysum Odoritissimum
Honey Myrtle - Melaleuca teretifolia
Juniper berry - Juniperus communis
Juniper (Utah) - Juniperus osteoperma
Larch - Pinus resinosa
Laurel - Laurus nobilis
Lemongrass (West Indian) - Cymbopogon citratus
May Chang - Litsea cubeba
Melissa - Melissa officinalis 
Myrtle - Myrtus communis
Niaouli 1,8 cineole - Melaleuca Quinquenervia
Norway Pine - Pinus resinosa
Oregano - Origanum vulgare
Pinion Pine - Pinus redulis
Plai - Zingiber Cassumunar
Ponderosa Pine - Pinus ponderosa
Rhododendron - Rhododredron Anthopogon
Rock Rose- Cistus ladaniferus
Saro - Cinnamosma fragrans
Scotch Pine - Pinus sylvestris
Silver Fir - Abies alba
Thyme ct thymol - Thymus vulgarus ct thymol
White Fir - Abies concolor
White Pine - Pinus strobus

Approximately 3-4 years from distillation:

Black Pepper - Piper nigrum 
Black Spruce - Picea mariana
Bergamot - Citrus bergamia
Citronella Java - Cymbopogon winterianus
Clove-Eugenia caryophyllata
Coriander - Coriandrum sativum
Elemi - Canarium luzonicum
Fragonia - Agonis fragrans
Eucalyptus - Eucalyptus dives
Fingerroot - Boesenbergia pandurata
Gingergrass - Cymbopogon martinii var sofia
Helichrysum - Helichrysum bracteiferum
Hemlock - Tsuga caneaensis
Lemongrass Rhodinol - Cymbopogon citratus ct rhodinol
Neroli - Citrus aurantium var amara 
Opopanax - Commiphora guidotti
Ravintsara - Cinnamomun camphora
Rosalina - Melaleuca ericifolia
Rosemary - Rosmarinus officinalis ct camphor/verbenone
Siberian Fir- Abies siberica 
Sitka Spruce - Picea sitchensis
Suganda Kokila  - Cinnamomum glaucescens
Sweet Marjoram - Origanum marjorana 
Tamala ct linalol - Cinnamomum tamala
Tea Tree - Melaleuca alternifolia
Turmeric - Curcuma longa
Vanilla - Vanilla planifolia
White Spruce - Picea glauca
Yarrow - Achillea millefolium

Approximately 4-5 years from distillation:

Bergamot Mint - Mentha citrata
Cardamom CO2 - Elettaria cardamomumBasil - Osimum basilicum ct linalool
Clary Sage - Salvia sclarea
Geranium - Pelargonium x asperum
German Chamomile - Matricaria recutita 
Ghandi Root - Homalomena aromatica
Ginger - Zingiber officinale
Helichrysum - Helichrysum italicum
Ho wood - Cinnamomun  camphora ct linalol
Jasmine Absolute - Jasminum grandiflorum 
Lavender - Lavandula angustifolia 
Linalol berry - Bursera delpechiana 
Neroli/Petitgrain Co-distill - Citrus aurantium var amara 
Palmarosa - Cymbopogon martini 
Peppermint - Mentha x piperita 
Petitgrain - Citrus aurantium 
Roman Chamomile - Chamaemelum nobile 
Rose/Geranium co-distill - Rosa damascena/Pelargouium
Rose Otto/Absolute - Rosa damacena 
Rosewood - Aniba rosaeodora 
Spike Lavender - Lavandula latifolia 
Thyme (Benchmark) - Thymus zygis loefl l. 
Thyme ct linalol - Thymus vulgarus ct linalol
Wild Mint - Wild Mint
Xanthoxylum - Zanthoxylum armatum
Ylang Ylang - Cananga odorata

Approximately 6-8 years or longer:

Balsam Capaiba - Copaifera officinalis
Balsam Poplar - Populus balsamifera
Blue Cypress - Callitris intratropica
Carrot seed Daucus carota
Cedarwood - Cedrus atlantica 
Cedarwood - Juniperus virginiana 
Myrrh - Commiphora myrrha 
Patchouli - Pogostemom cablin 
Sandalwood - Santalum album
Spikenard - Nardostachys jatamansi
Vetiver - Vetiveria zizanoides

General shelf life from a chemical family perspective:

About 1-3 years – Monoterpene rich oils, Monoterpene/Oxide (cineole) rich oils, Monoterpene/ Aldehyde rich oils, Monoterpene/Monoterpenol rich oils.

About 3-5 years – Monoterpenol rich oils, Monoterpenol/Ester rich oils, Ketone
and Phenol rich oils (Phenols are closer to 3 years).

About 6-8 years, or longer – Sesquiterpene rich oils, Sesquiterpenol rich oils.