Originally Posted by
syfi
From what I've read on the MB forums, no one ever changes that o-ring. It has never been reported to leak, and those that did change it report that the stem does not like being taken apart and put back together. It easily wears down the connection, causing it to break down and become unusable. Consensus is to best just leave it alone.
Also another cool trick with the One of the O-Rings is (can’t remember which one) it is the PERFECT size for the O-Ring on the oil dipstick.
Which is a failure problem in some cars (like mine) where the crank case builds up a lot of pressure and will shoot the dipstick out along with a few quarts of oil. OUCH
bought a new oil filter set 5$ and replaced the O-Ring