i believe that's the lack of oil in the timing chain part on startup, the only way to help stop it it's to intstall an oil accumulator, or add a little more oil in the engine, but with the amount of miles you have on your car, i would guess your car to last more than a year with that noise without any problems, it's more of a nusance than a problem. but hell i could be wrong, just wait for someone else to reply to this thread with a better answer.