Check two grease thickeners
11-family chart. General thickener compatibility only—specific grease products can still behave differently.
Generic compatibility guidance says this combination may be compatible; identify the actual polyurea formulation and verify the products before mixing.
I don’t know the thickener
Check the product technical data sheet for “thickener,” “soap type,” or “thickener system.” Grease color and NLGI grade do not identify compatibility.
Grease thickener compatibility matrix
Tap any cell for a plain-language result.
On narrow screens, scroll the chart horizontally. Select a cell to load that grease pair into the comparison above.
| Thickener A ↓ / B → | Al complex | Barium | Ca 12-OH | Ca stearate | Ca complex | Ca sulfonate | Clay | Li 12-OH | Li complex | Polyurea | Sodium |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Aluminum complex | |||||||||||
| Barium complex | |||||||||||
| Calcium 12-hydroxy | |||||||||||
| Calcium stearate | |||||||||||
| Calcium complex | |||||||||||
| Calcium sulfonate complex | |||||||||||
| Bentonite clay / non-soap | |||||||||||
| Lithium 12-hydroxy | |||||||||||
| Lithium complex | |||||||||||
| Polyurea (generic / subtype unknown) | |||||||||||
| Sodium |
Matrix source: Leahy-Wolf’s published grease compatibility chart. “Compatible” is a general thickener-level indication, not approval to mix two specific commercial greases.
How do you use a grease compatibility chart?
Find the thickener used in the grease already in the equipment, then compare it with the thickener in the replacement grease. Compatible means the general chart indicates the thickener systems can usually be mixed without a major consistency problem. Borderline / verify means compatibility can vary and testing is recommended. Incompatible means the combination should not be treated as mixable without a controlled changeover and product-specific guidance.
These categories screen thickener-system compatibility. They do not prove that two finished products match in base oil, additives, viscosity, temperature range, load capability, seal compatibility, approvals, or warranty requirements.
Can lithium complex and polyurea grease be mixed?
Generic grease charts often place lithium complex and polyurea in the borderline / possibly compatible category. That is not the whole story: ExxonMobil’s 2024 compatibility chart separates polyurea into shear-unstable and shear-stable formulations and gives different results for some pairings. Use the Polyurea type selector above when the formulation is known; otherwise keep it set to “Unknown / generic polyurea.”
If the existing or replacement product is described only as “polyurea,” do not assume it behaves like a specific polyurea subtype. Confirm the product data with the lubricant manufacturer before mixing.
How can you identify a grease thickener?
Check the product technical data sheet, lubricant selection guide, or manufacturer documentation for the thickener chemistry. Common labels include lithium complex, lithium 12-hydroxystearate, calcium sulfonate complex, aluminum complex, bentonite clay, polyurea, and sodium.
Do not identify compatibility from grease color or NLGI grade. Color is usually a dye or pigment, while NLGI grade describes consistency rather than thickener chemistry.
What should you do when changing to a different grease?
First confirm that the new grease is suitable for the equipment and operating conditions. Then check thickener compatibility and ask the lubricant supplier whether the two finished products can be mixed. If compatibility is uncertain or unfavorable, follow the equipment and lubricant manufacturers’ changeover instructions, which may require cleaning, purging, shorter relubrication intervals, or monitoring during the transition.
Do not use a compatibility chart to determine fill quantity or purge volume; those depend on the bearing, housing, lubrication system, and manufacturer procedure.
How is grease compatibility tested?
ASTM D6185-24, Standard Practice for Evaluating Compatibility of Binary Mixtures of Lubricating Greases, evaluates actual grease mixtures using properties such as dropping point, worked penetration, and storage stability. It is a testing practice—not a universal table that declares every grease with the same thickener compatible.
Laboratory testing is especially useful when a changeover will leave a meaningful amount of the old grease in service, the application is critical, or the products’ technical guidance does not agree.
Common grease compatibility questions
Can two greases with the same NLGI grade be incompatible?
Yes. NLGI grade describes consistency. Two NLGI 2 greases can use different thickeners, base oils, or additive systems and may not be compatible.
Does the same thickener guarantee compatibility?
No. Sharing a thickener family is a favorable starting point, but finished greases can still differ in additives, base oils, and formulation. Confirm the actual products for critical applications.
What happens when incompatible greases are mixed?
The mixture can soften or harden excessively and may show increased oil separation. The effect can become more pronounced with higher temperature or mechanical shearing.
What if I cannot identify the old grease?
Do not guess from color or consistency. Check maintenance records, labels, product data sheets, or supplier information. If the existing grease cannot be identified, treat the change as an unknown-compatibility case and follow a controlled changeover procedure.
Sources, methodology and limitations
This page converts published qualitative grease-thickener guidance into an interactive lookup. The 11-family matrix uses the public Leahy-Wolf Grease Compatibility Chart categories (YES, POSSIBLY, NO), normalized here as Compatible, Borderline / verify, and Incompatible. The chart is presented in a new interactive format rather than reproducing source artwork.
Polyurea refinement uses ExxonMobil, Grease: its components, consistency and compatibility (2024), which distinguishes shear-stable and shear-unstable polyurea. ExxonMobil describes its chart as a general guide and recommends laboratory compatibility testing when changing grease types.
Testing context is based on ASTM D6185-24. A separate current manufacturer reference, Lubrication Engineers Grease Compatibility Chart, Rev. 07/08/25, also describes grease compatibility charts as a starting point and notes that additional testing may be warranted.
For lubricant viscosity rather than grease mixing, use the Oil Viscosity Chart. Return to Engineering Charts & Tables.