I pulled the codes on my 2001 5.4L expedition and it said the #7 cylinder was misfiring so I am in the process of changing the spark plug and as I took it out I noticed there is a lot of oil in the piston chamber. Any ideas on why oil would be there? The motor has 175,000 miles. Thanks.

 

You mean oil on the firing part of the plug? That would be worn rings or valve guide seals.