I spilled some gas on my SMPC the other day while re-fueling the tender. I can only assume this might contribute to breaking down the seals. This set of seals is from '97 and needs to be replaced anyhow, but for future reference, does fuel cause much damage to them? I know there's types of rubber that are more resistant to petroleum products.
As the watches are designed for diving, I would say that it is not going to be sealed with a rubber seal that is petroleum resistant. If something similar happens again, I would suggest that you wash the watch completely at the first convenient moment.
The sun evaporated the petrol very quickly, so I wasn't keen to flush it with water (especially given the age of the seals). I'll need to be more careful around "boat stuff" until it goes in for servicing.
Its an interesting question, but I'm really not sure. Doubt it would do any rapid damage, particularly as the seals on those watches are over-designed considerably. Petrol won't do damage as much as salt water will (incidentally, a trick used in the 50s and 60s instead of servicing was to take the caseback off, and drape a watch over a container of kerosene to allow the vapor to lubricate the movement, whether it worked or not is debatable, but it didn't seam to do any harm either).
Petrol dissolves most black rubber, some faster than others. The outer layer goes sticky like tar. I've had some terrible messes to clean up (mostly due to my own carelessness).