Please correct me if I'm wrong.

[cato]

I own an Aqua C Remora skimmer. More than once people (and I think the owners manual) have told me to be sure and lubricate the rubber o ring, that goes around the skimmer cup, with petroleum jelly. This will help keep it from breaking prematurely.

Correct me if I'm wrong but doesn't petroleum degrade rubber?

[albinooscar]

Not if the rubber was engineered for use with petroleum.

There are a lot of uses for rubber oring seal including hydraulic systems and hydraulic fluid is pretty harsh stuff.

Ron