I use conventional high temp wheel bearing grease in the T bar sockets. It is nice and thick and little risk of dripping out.

If the sockets are dry, the T bars will creak and groan as they work. I think they need the lube and protection from dirt, moisture and corrosion.

I use the same conventional high temp bearing grease for the wheels and "heavy duty" moly grease for suspension joints.

This has worked well and keeps things simple.