New Additive Component

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Staff member
Jun 5, 2002
Iowegia - USA
This one may be a bit tougher:

The search to replace ZDDP has benn ongoing for many years now since it was postulated that the compounds in ZDDP poison catalytic converters.

Much research on these new liquids shows promise as a replacement for ZDDP and other organo-metallic compounds.

Any time you reduce the organo-metallic content of an engine lubricant, you reduce metallic ash deposits on valves and other components.

This new compound is an oil-miscible trihexyltetra-ecylphosphonium bis(2-ethylhexyl)phosphate.

In Ring-on-Liner tests in a base oil with the same concentration as ZDDP, this liquid showed a maximum COF of 0.075 whereas the ZDDP mixture showed a COF of 0.215, a huge reduction in COF.

This liquid showed a 50% reduction in wear when tested against the ZDDP mixture at 100C.

This liquid was stable up to about 300C.

What are the functional name(s) of this liquid, and what is the professional designation for this new liquid?

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Functional names for additive components are listed here:

Antifoamant or foam inhibitor

Antioxidant or oxidation inhibitor


Extreme Pressure Additive





Friction Modifier

Metal Deactivator

Oxidation Inhibitor

Rust Inhibitor

Pour Point Depressant

Seal Conditioner


Soot Control or Soot Inhibitor

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It's a phosphonium-based ionic liquid used as a liquid lubricant and is known for its solubility in PAO. I suppose that would make it a friction modifier.
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This new liquid has a professional designation as an ionic liquid (IL), and can be used as a friction modifier and anti-wear additive in motor oil.
Ionic Liquids show promise as a new additive that reduces friction and wear, so they are considered as functional Frictiom Modifiers (FM) and Anti-Wear (AW) additives, a "Multi-Functional" additive.

An introduction to ILs can be found in the April 2010 issues of the S.T.L.E's publication, TLT.

A good in-depth review of IL chemistry can be found here:

A Review of Ionic Liquid Lubricants by
Anthony E. Somers, Patrick C. Howlett, Douglas R. MacFarlane, and Maria Forsyth of the University of Victoria, Australia, Lubricants 2013.

Also referenced in this other forum is a discussion of ILs as well:
New additive....

As of this writing there are about 120 IL's being investigated as both additives and as base oils for various applications.

Route66mike wins the Piston Cup Lapel Pin for his response.
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