MolaKule
Staff member
Metallocene PAO (mPAO) verses conventional PAOs (cPAO)
By MolaKule
Sometimes a White Paper or technical article comes about from a question by one of our astute BITOG members and this is one of those.
Note: cPAO's are NOT to be confused with conventional mineral oils. It is simply a way to differentiate between these two types of PAO's.
mPAO's are produced utilizing a metallocene catalyst. This novel catalyst allows the base oil manufacturer to control how the linear alpha olefins react.
mPAO's consist of a range of high viscosity PAOs that have been designed to provide ultra high viscosity indicies, improved low temperature fluidity and combined with shear stability equal to or better than standard cPAOs.
(For a discussion of conventional PAO's, See Section II: Synthetic Base Oils group IV and V at: https://www.bobistheoilguy.com/ A Review of Mineral and Synthetic Base Oils)
In chemistry, a metallocene is any of a group of organometallic compounds that consist of a metal atom bonded between two cyclopentadienyl (or similar aromatic) rings in a sandwich structure, used especially as catalysts in polymer synthesis.
Molecularly, mPAO's have a uniform comb structure that lacks short side chains while cPAO's have long and short side chains in a random orientation on either side of the backbone.
While cPAO's are in no way inferior, mPAO's offer certain advantages over cPAO's.
Some of the advantages touted for mPAO's are:
1. Higher viscosity indices
2. Better low temperature fluidity
3. Enhanced film thickness at higher temperatures reduce wear
4. Lower foaming tendencies
5. Lower traction properties which translate to greater energy efficiency
Most mPAO's are available in 65 to 300 [email protected] viscosities.
In gear oil formulations, approximately 5-7% of an mPAO gives rise to higher film thicknesses at elevated temperatures and can replace conventional thickeners, such as polyisobutylene's, which can reduce cold temperature performance.
In low viscosity motor oil formulations, approximately 0.5-3% of an intermediate viscosity mPAO gives rise to higher film thicknesses at elevated temperatures and can reduce the levels of VII's needed to maintain viscosity and film thicknesses.
Some of the major manufacturers of mPAO's are DuraSyn (INEOS), SpectraSyn Elite (Exxonmobil), and Synfluid (Chevron Phillips).
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