Would applying lithium grease to plastic make it brittle? I greased the clips on my new passenger grab handle when i installed it, and a year later, the clips broke when my friend touched it. So should i leave the new handle dry when i put it in?

I've used it on some of the 2000 rear window regulators without any apparent issues (yet). Any warning labels about using it on certain plastics?

Any kind of petroleum-based grease will contain emulsifiers, surfactants, and especially breakdown products, that could attack petroleum-based plastics and rubbers. This property will increase with age, as the petroleum breakdown is accelerated by exposure to heat and UV.

In short, the use of petroleum-based lubricants can accelerate the "natural" heat and UV degradation of certain plastics.

For vinyl, plastic and rubber...particularly on interior parts...I would advise you to stick to silicone-based lubricants (or perhaps synthetics that specifically state they are OK for use on plastics--though this is a distant second best, in that these products will still contain emulsifiers and surfactants that can soften or damage certain plastics).

Thanks agrazela. I'll go get some silicone grease.