What a Jaipur Bearing Lab Found When It Ranked EV Greases

The four greases and the eight metrics

The Lubricants 2025 study (13(3), 108) from National Engineering Industries, Jaipur, with the University of Ljubljana, did something Indian grease marketing rarely does: it put four candidate greases for EV motor bearings through a multi-metric scorecard and published the ranking. The four: a polyurea on ester oil with an ionic liquid, a polyurea on PAO, a polyurea on ether-type synthetic oil, and a lithium grease on PAO as the incumbent reference. Eight metrics spanning noise, electrical behaviour, bleed, wear and physical consistency were scored. Overall suitability ranked polyurea-ester (with IL) first, polyurea-PAO second, polyurea-ether third, lithium-PAO last. We cite it as literature under stated conditions — from a bearing manufacturer's own research arm, which makes it more credible, not less worth reading critically.

What the paper is evidence for

Above all it is evidence that 'polyurea' is not one product. The same thickener family on three different base oils produced three different rankings across the metrics. Thickener brand loyalty and base-oil afterthought are both refuted in one table: the pairing is the product.

Why ester+IL was quiet and conductive

The polyurea-ester-IL grease won the overall score on the strength of two EV-critical behaviours: it was the quietest and the most conductive of the set. The plausible mechanisms are not exotic. Ester polarity gives strong surface affinity and boundary behaviour, which shows up acoustically in a motor bearing; the ionic liquid raises conductivity, giving shaft charge a path that is not an arc through the contact. For an e-motor designer worried about both NVH and electrically induced bearing damage, that pairing addresses the two fears in one drum. Note what the paper does not claim: that this grease is universally best. It won the overall score, not every row.

What it is not evidence for

A four-candidate scorecard is not a market verdict. The study is not evidence that ester-IL is right for your motor's temperature, your customer's cost ceiling, or Indian ester supply economics; it is not evidence about long-term oxidation life at the IL treat used; and the conductivity result depends on the specific IL and dose, which are not interchangeable across anions. It is also not a certification of any kind — no OEM approval follows from a journal ranking.

Why PAO polyurea won bleed and wear

The runner-up tells the more practical story for a blender: polyurea-PAO bled the least and wore the least. PAO's non-polar character and the polyurea network's oil-holding give controlled, low bleed — the classic sealed-for-life e-motor requirement — and the wear result shows the combination still feeds the contact. Least bleed plus least wear is the conservative engineer's podium finish, which is why PAO-polyurea remains the default recommendation where conductivity is handled elsewhere (shaft grounding) and quietness targets are conventional. The lithium-PAO reference landing last is its own lesson: the incumbent thickener family lost on EV-relevant metrics, whatever its decades of general-purpose credit say.

What a formulator changes on the bench

Steal the scorecard, not the winner:

• Eight-metric discipline: build your own scorecard — noise (grease noise tester), resistivity, bleed (D1742), wear (D2266 or rig), worked penetration (D217), drop point (D2265), low-temperature torque, oxidation (PDSC D5483) — weighted by what your customer's motor actually fails.
• Pairing arms: your polyurea on ester and on PAO from your own suppliers, with and without an IL arm, because supplier esters differ and IL anions differ.
• Cost column: raw-material cost per drum beside every metric — ester-IL economics in India are not Slovenian laboratory economics.
• Honest gate: any candidate must beat your current SKU on the customer's failing metric, not tie it overall. Context: EV motor bearing grease and polyurea manufacturing.

How an Indian blender should read a paper vs copy a paper

Copying this paper would mean ordering the winning chemistry. Reading it means adopting the method: candidate set, metric set, weighting, and published honesty about which grease won which row. An Indian blender's candidate set will include locally available esters, PAOs and Group III options the Jaipur lab did not test; the metric weights will follow the customer's motor, not the paper's; and the deliverable is a scorecard your sales team can defend in a customer's engineering review. It also gives your QC lab a template for incoming-supplier comparisons, which is where rankings quietly rot.

The design-around question

The design-around question: which two metrics does your customer's motor actually fail today — noise, discharge damage, bleed-out, wear — and which base-oil/thickener pairing from your matrix addresses those two rows, rather than chasing the paper's overall winner? The best EV grease for your customer is the one that wins their failing rows at a cost their BOM survives.

What Lubechem will and will not claim

Lubechem Consultant is an independent formulation house in New Delhi, led by Er. Manoj Kumar and practising since 2010. Lubricants 2025, 13(3), 108 is cited as literature: an Indian bearing manufacturer's multi-metric EV grease ranking, valuable precisely because it is domestic, recent and honest about row-level winners. It is not a Lubechem result, not our data, and not a specification for your motor.

What we will do is rebuild the scorecard on your candidate SKUs and your customer's failure modes — and say so when the boring PAO-polyurea is the right answer for your duty, as it often is. If you have two or three candidate EV greases and one failing motor application, send the TDS sheets and the failure description. The scorecard conversation takes one meeting; the screen takes a few weeks.

What the paper is evidence for — and what it is not

Literature and prior art

Citations below are orientation, not a freedom-to-operate opinion. Lubechem does not copy claimed compositions and does not treat a patent as a product endorsement.

1. Lubricants 2025, 13(3), 108 — Shekhawat et al., NEI Jaipur / University of Ljubljana — cited as prior art or literature, not as a product Lubechem sells
2. BIS IS 7623 lubricating grease — Indian grease certification path
3. BIS IS 13656 engine oils — automotive oil certification path
4. CPCB used-oil EPR framework — producer obligations; targets change — check the live gazette

Related formulation pages

• Ev Motor Bearing Grease India
• Polyurea Grease Manufacturing
• India