Question 1

Are water-soluble PAG base oils compatible with lithium complex grease thickeners?

Accepted Answer

Generally, standard water-soluble PAG base oils exhibit poor compatibility with lithium complex thickeners, often resulting in grease softening and oil separation. However, specialized oil-soluble PAGs (OSPs) or carefully formulated co-base systems can achieve stable compatibility. Conduct ASTM D6185 compatibility testing to verify.

Question 2

Which grease thickeners are highly compatible with polyurea PAG grease?

Accepted Answer

Polyurea thickeners typically show good to excellent compatibility with both oil-soluble and water-soluble PAG base oils, making them a preferred choice for high-temperature applications. This combination delivers exceptional oxidative stability and prevents the formation of sludge or lacquer.

Question 3

What happens if you mix incompatible grease thickeners with PAG base oil grease?

Accepted Answer

Mixing incompatible grease thickeners with PAG base oils can lead to a severe drop in consistency, causing the grease to liquefy and run out of the bearing. Conversely, the mixture can harden significantly, preventing proper lubrication and leading to rapid component wear.

Question 4

How does ASTM D6185 help determine thickener compatibility in PAG greases?

Accepted Answer

ASTM D6185 outlines the standard practice for evaluating the compatibility of binary mixtures of lubricating greases by testing them in various ratios (10:90, 50:50, and 90:10). The standard evaluates dropping point, shear stability, and storage stability.

Grease Thickener Compatibility Diagnostic Checker