Help Me Read my Spark Plugs!

Information:
2013 Toyota Tacoma. Base Model. 2TR-FE (Four Cylinder) Motor. Truck has 60,000 miles on it, and I've had truck since new. Religious Oil changes every 5k.

Changed my spark plugs today. The plugs in cylinders 1 and 4 (according to my little drawing) had oil on the threads of the plug. Ignition Coils on all cylinders were completely clean and appeared normal. The spark plug in cylinder 1 had a small amount of oil in the base of the plug (nearest to the ceramic part) where as Cylinder 4 had a pretty even amount on all of the threads. No oil deposits existed on the tips of any plugs, and the truck does not burn oil. What is going on? If it is my valve cover gasket, wouldn't there also be oil on the coil pack?

Someone who's older and wiser than me give me some insight.

Firewall
_____
| (4) |
| (3) |
| (2) |
| (1) |
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Front of Truck

 

I'm not familiar with the 4 cylinder in the Tacoma, but there should be an inner valve cover gasket that goes around the spark plug cylinders. If that leaks it can cause your issue.

For reference.

 

But if this was the case, wouldn't the coil packs have oil on them? What's so weird to me is the engine burns no oil, and the coils we're bone dry...

 

The leak is likely so little that you'll notice no oil consumption. The coil packs would only have oil on them if the leak was significant. Those o rings that seal the spark plug wells are almost certainly your issue.


If the leak was significant, those wells would start to fill with oil and cause misfires.

 

In your opinion is it worth replacing now or waiting a bit? It's got to be a tiny leak.

 

At this point it's not really hurting anything other than making a bit of a mess on the spark plugs. If you don't want to change them now, I would just keep an eye on it. When it gets worse go ahead and change it. Reason being, like I said, once it does start making contact with the coils it will short out and cause problems. When you change them, change the regular valve cover gasket also. They should be done as a set.

 

I read that your spark plugs think you forgot f'ing pictures of them

 

Yes. The #1 plug well seal is weeping a bit, that made it's base "wet"; the #4 is well leaking a bit and when you pulled the #4 plug the collected oil ran down onto the threads. The coil's are dry because the boot only extends partway down the ceramic and did not contact the accumulated oil. Changing the cam cover gasket on the 4-banger is not major project...