Hi Martin, here's the reply directly from WD-40 representative. ***Thank you for contacting WD-40 Company with regards to using WD-40 on o-rings. WD-40 is a multi-purpose light lubricating oil, which will displace water and moisture from the chain. The "WD" stands for water displacement and acts as a rust preventative on any metal surface. WD-40 will not dry out the rubber o-rings. We have found no visible effects on the surface of rubber and o-rings. Certain types of rubber will swell under prolonged immersion in WD-40 (this refers to long soaking and not just a spray).

WD-40 is also a cleaner, which will remove grime, dirt, tape, bumper stickers and oil. It is possible that if there is a special lubricant in the o-rings, WD-40 could act as a cleaner and remove that oil. The special lubricant would be replaced with WD-40. We are sure there are superior heavy-duty chain lubes on the market. There are several people who recommend using WD-40 on their chains. Perhaps some experimenting with WD-40, as a water remover and rust preventative followed by a heavier chain lube would fit your needs. The bottom line is WD-40 will not harm your o-rings, but it could remove a lubricant that was previously applied to the chain.

We recommend you only spray the area near the wheels, moving parts and other areas you want to clean off. We do not recommend spraying on the manifold or exhaust pipes. Please never spray WD-40 on a hot bike.
Thank you again for contacting WD-40 Company. Please let us know if we may be of further assistance.
Best regards, *