Hi Rusty
High Quality Polurea Greases are manufactured by Japanese Grease makers, don't know brands,
In the USA Exon Mobil, was Witco, and Shaffer, now Shell, there are others but these were pointed out to me by Dave Nash of Witco 15 years ago as the top three manufacturers and since then we have used the Exon Mobil ISO 220 base oil with very reliable results.
I do prefer the Exon Mobil products as they utilise a Passive EP system, CaCO3, no reactivity with moisture very passive grease,
Polyureas are not shear stable as they tend to "drop" the base oil under sever loading and once the pressure is remove the thickner will recombine with the base oil without too much change in the grease.
Noria (I think) has a chart on compatibility with other thickners and the polyurea tends to be the thickner that can handle some contamination from other grease thickners but when ever mixing any grease type the system should be pruged or repacked so + 90 % of the old product is removed, I'll check if I can find the chart and pop it up.
Regards
Rob S
www.rttech.com.au
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