About 3 years ago I noticed oil on the spark plugs on my 2000 Concorde 3.2, all on the driver's side. Today, I removed them and the 3 on drivers' side had still had oil on them with about the same amount of oil as before. The only symptom is a little bit of smoking. Quote from garage to replace the tube seals and the valve cover gaskets about $500 for labor only. Is this something that is necessary to fix?