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Zinc Dialkyldithiophosphate, C1-14 alkyl (ZDDP-type antiwear additive)

  • Corrosion inhibitors
  • CAS 68649-42-3
  • IUPAC: Phosphorodithioic acid, O,O-di-C1-14-alkyl esters, zinc salts

Zinc Dialkyldithiophosphate, C1-14 alkyl (ZDDP-type antiwear additive) (CAS 68649-42-3) appears in 1 of the 2,122 car-care products CarCareTruth tracks (as of August 2026).

Ingredient-level classification: Skin Irrit. 2 (H315) and Eye Dam. 1 (H318, serious eye damage). This is a C1-14-alkyl-ester ZDDP variant distinct from the shorter-chain CAS 68457-79-4 (see zddp.md); the two are chemically related zinc dialkyldithiophosphate salts but are separately registered CAS numbers with their own SDS hazard profiles. At the 1-5% weight concentration typical in manual transmission fluid, the mixture-level classification is diluted to Serious eye damage/eye irritation Category 2A (H319) rather than the ingredient's own Category 1 (H318) -- this is expected GHS mixture-dilution behavior, not a transcription error.

Zinc dialkyldithiophosphate (ZDDP) with C1-14 alkyl ester groups (CAS 68649-42-3) is an antiwear and extreme-pressure additive used in gear oils and manual transmission fluids. Under the boundary-lubrication conditions found between meshing gear teeth and synchro cones, it decomposes to form a sacrificial zinc/phosphorus/sulfur tribofilm that protects metal surfaces from wear.

This is a distinct CAS registration from the shorter-chain ZDDP variant (CAS 68457-79-4) already documented in zddp.md for motor oil. Both are zinc dialkyldithiophosphate salts and share the same general hazard family (skin/eye irritation, aquatic toxicity, zinc heavy-metal content), but this C1-14-alkyl-ester variant's own SDS lists Eye Dam. 1 (H318) at the ingredient level, one category more severe than the shorter-chain variant's Eye Dam. 2 (typically). At the 1-5% weight concentration used in Honda's manual transmission fluid, GHS mixture-classification math dilutes this to Serious eye damage/eye irritation Category 2A (H319) at the mixture level, which is what appears on the product's own SDS Section 2 and drives the product's health score.

Regulatory status

  • Not Prop 65 listed in the US (CAS 68649-42-3 confirmed absent from the OEHHA Proposition 65 chemical list, 2026-07 cross-check)
  • Classified Aquatic Acute 2 (H401) and Aquatic Chronic 3 (H412) at the ingredient level in the US GHS/OSHA HazCom system

Health & environment profile

VOC
no
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
yes
Biodegradable
no
Bioaccumulative
no
Persistent
yes
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
2/5
Purpose: Antiwear/extreme-pressure additive in gear and manual transmission fluids; forms a protective tribofilm on gear and synchro metal surfaces under boundary lubrication

Common questions about Zinc Dialkyldithiophosphate, C1-14 alkyl (ZDDP-type antiwear additive)

What is Zinc Dialkyldithiophosphate, C1-14 alkyl (ZDDP-type antiwear additive) used for in car care?
Antiwear/extreme-pressure additive in gear and manual transmission fluids; forms a protective tribofilm on gear and synchro metal surfaces under boundary lubrication
Is Zinc Dialkyldithiophosphate, C1-14 alkyl (ZDDP-type antiwear additive) a VOC?
No. Zinc Dialkyldithiophosphate, C1-14 alkyl (ZDDP-type antiwear additive) is not classified as a volatile organic compound (VOC).
Is Zinc Dialkyldithiophosphate, C1-14 alkyl (ZDDP-type antiwear additive) on California's Proposition 65 list?
No. Zinc Dialkyldithiophosphate, C1-14 alkyl (ZDDP-type antiwear additive) is not on California's Proposition 65 list.

1 product 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.