I just use the SuperTech (Wal-Mart) Hi-temp Extreme Pressure wheel bearing grease, lithium-based. The reddish-purple stuff. That said, you should be good with anything labeled for use as chassis grease. Check the NLGI rating on the container. Careful with the amount you force into the boot, if any of them is old and cracked it may burst. You just need to get it firm to the touch.
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