You should refer to your manual or the manufacturer's website. Al-Ko for example says:
"Use a high temperature, automotive type wheel bearing grease produced by a reputable manufacturer. The soap type should be lithium complex or equivalent. Use NLGI Grade 2 product with a minimum dropping point of 440F".
Dexter grease specsAs an example, specs from a grease manufacturer:
Red 'N' TackyI believe the dropping point temp. is important. I've read that Lucas Red 'N' Tacky and Mystik have good reviews.