nthach:

Having grown up in the Napa Valley, a few miles from you, I know there are no significant environmental reasons for this strange malady. These should be the least troublesome rubber items on your vehicle. Something is causing this, obviously, so search it out with a bit of logical detective work. Does the muffler hang fairly straight but low when you disengage all the donut hangers? If not, and it droops far to the side, then you are likely trying to pull the whole asembly into its proper alignment with the donuts, which can greatly stress them and may lead to premature failure. Have you replaced the muffler with an aftermarket unit which may have placed the donut(s) in closer proximity to the heat source than would an OEM? Are you using all the donuts? My old sedan has four to suspend the rear muffler, how about yours? Are they always new donuts? Always the same one?

Just thoughts...good hunting,

230/8