Suspension greasing

I have a 6 inch suspension lift on my truck and it’s started squeaking and everyone has said it needs greased. What is the best lubricant to do this with?

 

If the ifs springs or rear leafs are doing the squeaking which i've never heard of anyone applying grease. When i had an old 78 toyota wolverine the leafs front, and rear use to pop and squeak. Had a suspension company in the state here manufacture all new leafs to the same size. They used these rubber insulators in-between some of the leafs. Truck rode way better and quiet.
As far as any other component thats related to the suspension movement...i always used the same old plain grease you'd use for ball joints.

 

Lucas red and tacky. I put that shit on everything.