what kind of grease to use on front shocks
It sounds like the fork was non-functional or stuck.  Simply greasing the uppers isn't going to resolve the problem - you likely need to rebuild the entire shock assembly, replacing seals, lubricating internal parts, etc.  Every fork is a bit different, so you'll need to find service instructions for the specific manufacturer/model you own.  Or, have the local bike shop do it - it shouldn't be more than a few hours labor.