Originally Posted by
cyccommute
I don't think you realize that "synthetic" oils and greases are synthesized from petroleum. They share the same properties as "petroleum based" lubricants otherwise they couldn't be used in the same applications.
You also can't make the broad statement that "petroleum based greases can deteriorate rubber". Some might but others don't. Petroleum based products cover too wide a range of materials to make that claim. Even saying "rubber" covers too broad a range of materials to make that claim. "Rubber" includes a whole host of elastomeric materials with vastly different properties. Natural latex doesn't stand up to much of anything well but, thankfully, not much natural latex is used in bicycle parts. Buna rubber, which is pretty common in bike parts, stands up to petroleum products quite well.
I should have said
silicone based instead of
synthetic. Obviously the Mobile 1 product is not silicone based. That was my mistake.
It is generally accepted that petroleum based lubricant run the risk of deteriorating rubber and plastic o-rings, seals, etc. We can argue about what constitutes a petroleum based lubricant or discuss the definition of rubber but the safest thing to do is to avoid petroleum based products if there is any doubt about contact with plastic or rubber.
I err on the side of caution. People are free to use what they want, or to just laugh at me as is the case with your response. It wasn't the first and won't be the last. I really don't care.
For those who have an interest in the topic apart from mocking however, Napa Sil-Glyde is a good, general purpose silicone grease and dirt cheap.
