Originally Posted by jannisa
You are correct, the WD40 is primarily not a lubricant, it's a rost-off/penetrating oil mainly and water-displacing spray.
I actually have no scientific data that proves it is not harmful for the rubber seals but I have been using it for years on cars with no problematic symptoms at all and I have been suggested to use it by mechanics and friends who have also been using it for years.
If you have the patience I believe the best product you can apply is pure vaseline (not in creamy form). I have tried over the years vaseline, silicon, hts lubricant, armor all for plastics, autoglym for leather, handcream, wuerth gummi and use only wd40 now.
Another thing I noticed when I too used silicon based sprays and products is that the film they built up on the rubber had an unnaturally greasy appeal plus it kinda felt a bit ''toxic''/burning my hands after a bit of a longer exposure. I have also heard that silicon based products might eaten up rubber seals in the long run, again their evidence was rather experimental.
I 've noticed what was mentioned in the link you attached but so far I have not seen any sign of fade in my case. Perhaps the folks with the boats believe it is snake oil and apply it everywhere even on electrical connections and we don't know if they cleaned the rubber first before bathing it with wd.
Give it a try once since you already have it and see how it feels, you won't hurt anything and please report back.
(or send me the bill in 10 years
Thanks for sharing all of your experiences! Now I also used all of my WD40 to clean off some sticky road surface material which could not come off during normal car wash. It worked wonders!
And I actually agree with your opinion about silicone oil. I will try to find some vaseline next.