What does it mean when my spark plugs are covered in oil?
The person did not say if it was on all the spark plugs or on the engine side or the outside where the wires connect. I imaginge he/she did not remove the plugs so the oil is on the outside. Rings or seals would not cause this; they would cause oil burning and they would probably not go all bad at once. Maybe they left the oil cap off, which would cause oil to blow out and get on the plugs and elsewhere. A pcv valve pulled out or such could also cause oil to blow out. Maybe they spilled oil that blew back on the engine. All this is a lot of speculation; a knowledgeable person needs to look at the engine; a good first step would be to take it back to the place the oil was changed to check for simple/obvious problems.
