My door began slamming over the past four to six months, and there's a trail of this sticky mess dripping down the glass door and collecting like black tar on the threshold under the door closer. Can I assume that the sticky black mess, which is nearly impossible to remove, is indeed either oil or hydraulic fluid?

Answer

Yes, I think your diagnosis is absolutely correct!

Updated on May 1, 2018

Original Article:

How to Adjust Your Door Closer
By Tom Rubenoff
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