Here is a caution statement from Dexter FAQs.
BEARINGS - What is the proper bearing adjustment procedure and recommended grease?
Please review the Dexter Service Manual for instructions and specifications relating to bearing adjustment and lubrication. WARNING: It is important NOT to mix different types of grease thickeners. The grease that Dexter Axle uses has a Lithium Complex thickener. Mixing our grease with a Barium, Calcium, Clay, or Polyurea soap based thickener agent will cause adverse affects. This may include causing the two greases to harden, separate, become acidic, or pose other hazards and damage to the bearings.
Dexter manual
lists approved greases.