I have used motorcycle fork oil seems OK. And it can be had in different "viscosity" ratings. Not expensive. I think ATF could be used as well. Any thoughts out there? Clean and fill. Move them and look for leaks. Move them and see if the fluid level changes, that is a good thing, you are moving the air out. Single action shock will have resistance in one direction and double action shock will resist both ways.I just changed a set on a 48 Stylemaster. The hard part was the Caster, Camber adjustment. Not an issue on the trucks.
