Originally Posted by
easyupbug
I have been clear in the OP's case he needs a new seal, a lubricant will not help him. That said in my discussion with
smd4 on preventative maintenance, not repair, or chemical incompatibility, you can read from the Dupont Resource Center "MOLYKOTE® 55 O-Ring Grease is a silicone-based material that helps ensure positive lubrication and sealing by slightly swelling rubber O-rings and seals" which is standard industrial preventative maintenance practice that enhances the sealing and life.
I think you are misunderstanding what the Molykote is doing. From the
Dupont technical sheet:
DESCRIPTION
MOLYKOTE® 55 O-Ring Grease is a silicone-based material that helps ensure positive lubrication and sealing by slightly swelling rubber O-rings and seals. This product is heat-stable and oxidation-resistant and is serviceable from approximately
-65 to 175°C (-85 to 347°F).
How to use
MOLYKOTE® 55 O-Ring Grease should be applied using brush, grease gun, or automatic lubrication system. MOLYKOTE® 55 O- Ring Grease can be used in centralized lubrication systems. Do not mix with other greases.
MOLYKOTE® 55 O-Ring Grease has been shown to swell natural rubber. However, compatibility of the lubricant may vary with the plasticizer content of specific materials (especially elastomers). Small-scale compatibility testing should be conducted prior to the use of this product in any application.
MOLYKOTE® 55 O-Ring Grease should not be used with the following materials unless thoroughly tested for your specific application:
• Silicone rubber (SR)
• Polycarbonate (PC)
• Acrylonitrile-butadiene- styrene (ABS)
I read this as it is meant to swell
natural rubber o-rings. In my experience, that is a vanishingly small proportion of o-rings available and in common use. Buna, neoprene, and Viton are far more common. I’ve had a lot of o-rings swell and it’s never good for the sealing job they are meant to do.