I've searched and I can't seem to find proof of what this means. I think I remember reading that it's a sign that it's time for a rebuild.. I hope this isn't the case. It's a mazda reman motor now at abou it's' 75,000mile mark. I guess I should have known. Next step, compression check?

*Edit: And yes, the oil is on the thread side of the plug.

 

Gas and oil are often confused on plugs, are you sure that you didn't cold start the engine, then pull the plugs???

 

Hmm.. no, I had to drive 20 miles or so (about a half hour of driving total) to get the plugs, came back, let the motor cool down, and went to work. The car also doesn't like idling while cold, and will die often in the morning at anything less than operating temp. Now that you mention gas being a possible player, whatever film it is on the plugs is definitely a bit less viscous than oil is normally.

Now that I think about it, about 10 minutes after I parked the car when I got home, I started it up again and moved it a little in the driveway and shut it off. Could that be it?

 

yep, that is a possibility.

Next time, after driving for at least 15-20 minutes, park the car, wait for the engine to cool and then pull the plugs (without restarting the car).

See if you still have the problem then.

 

Were your spark plugs in tight?
If they are loose, fuel / oil tends to blow-by onto the threads.
Don't ask me how I know this. :P


-Ted

 

I just got this car a few days ago so I'm just going through the paces (tune up, inspection, etc.) so I wasn't the one who put the plugs in. When I took them out they seemed to be torqued down just about right though. I'm waiting on some plug wires to come in before I can run the next little test (the old wires literally came apart when I pulled the plugs) so I guess we'll see then! Thanks for the help guys, at least I have a little hope now.

Quick question. Why would the oil/fuel only show up on the leading plugs? The trailing plugs were perfectly clean.

 

Actually, some "mechanics" use motor oil on the spark plug threads as a last-resort anti-seize.
The previous person who put the spark plugs could've just done that.


-Ted