Has anyone ever experimented with WD-40?
I think 303 is good as a lubricant to help get your gaskets on and off, and as Imyers said, being gentle is key to longevity. If you lube them up, you don't have to work as hard to get them on and off. But I'm not sure if I buy into it actually prolonging the life of your gaskets.....
Which is why I'm wondering if WD-40 would also work as a lubricant and conditioner? Its chock full of good lubricating oils, is a water displacer (due to said oils), the oils penetrate great, and its awesome for cleaning. Contrary to belief, if you spray it on and rub it off, it will not leave an oily residue, but rather a nice slick lubed surface, very similar to 303.
"Coat rubber ties on boats to keep rubber from drying out"
"Keeps rubber door weather gaskets soft and pliable"
"Lubricates rubber bushing"
"Helps protect rubber trunk molding"
"Protects rubber gaskets around the sunroof"
"Lubricates rubber wiring grommets"
"Conditions synthetic rubber"
"Protects rubber seals on lawn and garden sprayers"
"Softens rubber o-rings"
"Cleans and conditions rubber on table tennis paddles"
"Cleans and lubricates rubber seals"
"Lubricates rubber insulation around storm door"
I'm willing to bet it would work awesome to prevent your gaskets from drying out.