What causes oil to fill the spark plug wells?
Documented on the 2012 Ford Mustang GT build
Published February 26, 2026
On this engine the most common cause is leaking spark plug tube seals and/or valve cover gasket failure that lets oil seep into the wells.
Full Answer
On this engine the most common cause is leaking spark plug tube seals and/or valve cover gasket failure that lets oil seep into the wells. A failed PCV or other localized leak is less likely than degraded tube seals.
Documented In This Build
Related Knowledge
Can I drive the car if the plugs are covered in oil?Do I need to replace the ignition coils too?Is this an expensive repair?How long will the repair take?How do I know if the PCV grommet is bad?What torque should I use for the coil mounting bolt?How often should I clean the fuel injectors?Can I use a pour-in fuel additive instead of an inline cleaning kit?
Related Parts
Dielectric grease
$6
Valve cover gasket set with spark plug tube seals
Motorcraft (typical OEM for Ford) / aftermarket equivalents$75
Spark plugs (set of 8)
NGK / Motorcraft$90
RTV silicone sealant (small tube)
$5
Engine degreaser / shop towels
$10
Related Tools
Torque wrench
Socket set & ratchet (including 10mm, 8mm, extensions)
Spark plug socket (5/8" or 13/16") with extension and swivel
Flat screwdriver / gasket scraper
Shop vacuum / compressed air
