Servo rust

Servo rust is an aliment that is, it would appear, quite persistent, pernicious, and all but impossible to eliminate once you have it. It may be more of a lingering annoyance than an actual mortal threat.

Fiction

2015 Robots in Disguise cartoon

Upon learning of the return of the long-thought-dead Starscream, Optimus Prime grumbled that the Seeker was "harder to eliminate than servo rust". Mini-Con Madness