Originally Posted by performanceisland

Guys the engine oil dip stick has an o-ring on it which is supposed to help keep it tight in the tube, however that OEM o-ring is actually to small form the factory, we always replace them with a thicker size to have it fit snug into the tube, this allows a tight seal, and it wont jump out on you, and will actually help keep dirt out unlike the factory o-ring which does nothing! I can't think of the exact size i'd have to take a look at my o-ring container. We figured this out one time ordering new dip sticks and even the o-rings alone form mercedes and they were all wrong (too thin).