Our van's sliding door was making a lot of creaking and groaning noises when the body would experience torsion, like turning on a hill, going over a curb, etc. I tried a lot of different lubrication ideas for all the door's contact points, and the combination of the following has knocked down the noise about 90%.
I used white lithium grease for most of the contact points, sprayed into a rag and wiped on with q-tips.
These mechanisms are sometimes referred to as 'pin cups'. I used white lithium grease on both the male and female parts.
Many people on the internet say that greasing this peg is very helpful for noise suppression. I did it, and it helped.
I used silicone spray on the surface of this rubber bumper.
