Should There be Oil On Your Spark Plug?

spark plug, oil on your spark plugReading spark plugs used to be at art that almost every mechanic knew.  They could tell by looking at the color of the electrode and insulator how old the plug was and how the car was running.  If you’re interested in learning this dying art, check out this cool article about Champion Spark Plugs.  So should there be oil on your spark plug?  Even if you’re not a spark plug whisperer, you still probably know that oil on a spark plug indicates a problem.

There are really only 2 ways you can get oil on your spark plug:

  1. Piston Ring Blow-By
  2. Bad Spark Plug Tube Seal

First, let’s talk about bad valve seals.  A bad valve seal will allow oil to drip from the cylinder head past the valve into the combustion chamber.  If you’ve got this problem you probably see a small puff of blue smoke when you start your car every morning.  This will not leave oil on your spark plug as the leak doesn’t happen fast enough to allow a significant amount of oil into the combustion chamber while driving so the oil burns up quickly after you start your car and your spark plug will be dry.

Bad piston rings will let combustion gases into the crankcase and engine oil into the cylinder.  If the blowby gets real bad, the oil can foul your spark plug. In this case an easy, but a temporary fix is to install a spark plug anti-fouler.  This device spaces the spark plug far enough out of the combustion chamber that it won’t get covered by so much oil.  If you suspect this a compression test of your engine can help you find out which cylinder has a bad ring and how bad it is.

Bad spark plug tube seals are the most common cause of oil on your spark plug.  The reality is the oil isn’t really on your spark plug but it’s pooled up in the bottom of the tube the spark plug sits in so when you pull the plug out it gets covered in the pooled up oil.  If this is the case, you’ll have oil on the tip of the spark plug as well as the white insulator and usually on the spark plug boot as well. This is caused by a bad spark plug tube seal. Replace the tube seal requires removing the valve cover and changing the valve cover gasket as well as the spark plug tube seals.

If the hard part repair doesn’t make sense for your vehicle, consider using BlueDevil Oil Stop Leak to restore your spark plug tube seals to keep your spark plugs oil free! 

You can pick up BlueDevil Oil Stop Leak at one of your local auto parts stores like:

  • AutoZone  
  • Advance Auto Parts
  • Bennett Auto Supply
  • CarQuest Auto Parts
  • NAPA Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys
  • Fast Track
  • Bumper to Bumper Auto Parts Specialists
  • S&E Quick Lube Distributor
  • DYK Automotive
  • Fisher Auto Parts stores
  • Auto Plus Auto Parts stores
  • Hovis Auto & Truck Supply stores
  • Salvo Auto Parts
  • Advantage Auto Stores
  • Genuine Auto Parts stores
  • Bond Auto Parts stores
  • Tidewater Fleet Supply
  • Bumper to Bumper Auto Parts
  • Any Part Auto Parts
  • Consumer Auto Parts

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spark_plug. jpg – By Pawzi – LIcensed by Getty Images – Original Link