Originally Posted By: Kamele0N
NEVER use ATE plastilube on rubber parts!!!! NEVER
That is the reason why I changed all the seals ( dust boots and rubber on sliding pins....because seller said plastilube is OK for rubber
As Jules would say, "correctamundo!"
The tube I have includes a warning on the back -- "Never apply to friction surfaces of the brake disc or pads,
nor to rubber parts"
The instructions have always referenced applications to areas like backing plates, piston heads, and pad ear contact areas -- all in the name to prevent squeal -- not as lubrication for the rubber parts.
ATE makes a separate brake assembly paste for parts like rubber piston seals when rebuilding calipers.
http://www.ate-info.de/en/details/produkte/ate-bremszylinder-paste-180-ml
It's confusing because ATE presents conflicting information itself, by stating Plastilube "is compatible with all metals and most O-ring materials" on its website, but then feeling the need to put a rubber warning on the tube (which older packaging has lacked).
It forces users to read between the lines, and unfortunately, the product to be mismarketed as suitable for a general rebuild grease, when it's not rubber safe, and against its intended usage. The fact that the brake cylinder assembly paste isn't distributed in the U.S. also encourages Plastilube's misuse.
The safest course is to consult the FSM. I know for certain that BMW specifies dry pins, which causes as much head scratching as dry plug threads, and no tire rotations, but while one may debate the reasoning, there is no ambiguity about their position.
If one feels the need to go against those recommendations, then a proven rubber safe grease like Dow Molykote 111 or something like Sil-Glide is in order.