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Butyl stearate

  • Esters
  • CAS 123-95-5
  • IUPAC: Butyl octadecanoate

Butyl stearate (CAS 123-95-5) appears in 2 of the 1,812 car-care products CarCareTruth tracks (as of June 2026). It is readily biodegradable.

Low toxicity. Not classified as a skin irritant, respiratory irritant, or carcinogen under GHS. Used in both industrial lubricants and personal care products at similar concentrations.

Butyl stearate (CAS 123-95-5) is a simple ester formed by the reaction of stearic acid (an 18-carbon saturated fatty acid found in animal and vegetable fats) with n-butanol. In lubricant formulations, it serves as a lubricity additive — it reduces friction between metal surfaces by forming a thin, adherent molecular film.

Because it is derived from a saturated fatty acid, butyl stearate is more biodegradable than petroleum-derived lubricant carriers. It is also used in cosmetics and personal care products as an emollient, which reflects its relatively low skin toxicity profile.

In multi-purpose lubricants, butyl stearate improves the "oiliness" of the base oil blend — it helps the lubricant adhere to metal surfaces under light load conditions, making it effective for hinge lubrication and light mechanical applications.

Health & environment profile

VOC
no
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
yes
Bioaccumulative
no
Persistent
no
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
4/5
Purpose: Lubricity additive and emollient — reduces friction between metal surfaces; used in lubricants, metalworking fluids, and cosmetics

Common questions about Butyl stearate

What is Butyl stearate used for in car care?
Lubricity additive and emollient — reduces friction between metal surfaces; used in lubricants, metalworking fluids, and cosmetics
Is Butyl stearate a VOC?
No. Butyl stearate is not classified as a volatile organic compound (VOC).
Is Butyl stearate on California's Proposition 65 list?
No. Butyl stearate is not on California's Proposition 65 list.
Is Butyl stearate biodegradable?
Yes. Butyl stearate has a confirmed biodegradable profile.

2 products contain this

Related

Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.