I was using both slide and seal lubes sold by Camping World on my slides until I had some troubles. Tech told me the best thing to use on rubber seals was baby powder or talc as it provided some "tooth" and made the seal roll better when slide was moved. Also told to clean the lube off of the slide mech. and keep clean. Lube was dragging dust, dirt particle thru the teflon seals and would degrade them.
Since following his recommendations 2 years ago, I have had no further problems
I used to lubricate my slide but started having problems with it going slow etc. I cleaned everything off and now just keep it clean under there and have had no problems just as janicenlarry above. I would recommend not using any lubes - just spray under there with WD40 now and then to clean everything off and wipe it down. Works for me!