I have read about this too. I believe that the seller will take it back if this is the case. I have used the Permatex did not have any problems. Which one are you using? Is it the Green one or the Pink one? Or you can buy the Kleen-Flo ones be sure its the Synthetic one.
Interesting. I just purchased a new 8 oz bottle of Permatex Synthetic Lubricant, Ultra Disc Brake Caliper Lube. It's green, # 24110. My old rule of thumb was that if it was synthetic and/or silicone based, it was safe for rubber parts. This new Permatex Lube does not mention anything about whether it is, or is not, safe for rubber. Rubber is not mentioned at all on the label. My last 8 oz bottle of CRC Synthetic Brake & Caliper Grease (it's black) specifically states it will not damage rubber or plastic parts, and I have found that to be true, as I have used it for many years without any issues.
Is it the green Permatex # 24110 that is causing problems with rubber parts?
Permatex 22063 and 24127 are the ones that swell the rubber real bad, even though it says it's safe to use on rubber.
I remember now which ones for sure are ok, SG-4 Sil-Glyde and what downloader posted, Kleen-Flo Eze Slide. The others
I am not sure if they are ok or not as Perm makes many products, some very good and some that are not safe to use on rubber even though they state otherwise.