Changed the plugs in the Mazda5 just now because it's been a little slow to start in the cold, I figured the OE Iridiums were worn and felt it was worth the $$$ to replace them now (88K) than later (100K service interval IIRC).
Worn a little on 2-4, but #1 was coated in oil, and lots of it. Fresh, too. Please tell me there's some silly valve cover o-ring or something that could be leaking...
(#1 is the one closest to the accessory drive BTW, I have to change the belt, too)
Which part of the plug is coated in oil?
If it's like a Miata, it's a bad valve cover gasket. I'm assuming you're not blowing dramatic amounts of oil or you would have mentioned it...
I had the same problem with my 91 Civic Si. I got a valve cover gasket set which included tube seals. It fixed the problem. Not sure that's your problem, but it's a thought.
Top (the socket came out oily)and bottom (electrode was coated, I could see oil on the piston top in the hole). Yes, the plus was still tight. No, the 5 hasn't lost/eaten any oil until now.
In reply to Fletch1:
The 2.3 doesn't have tubes or tube seals. Very odd design.
Checked the breather system? Maybe the PCV has taken a semi-permanent vacation?
Javelin wrote: Top (the socket came out oily)*and* bottom (electrode was coated, I could see oil on the piston top in the hole). Yes, the plus was still tight. No, the 5 hasn't lost/eaten any oil until now.
When you screwed the plug out, the oil in the tube drained into the cylinder and coated the electrode and piston top.
Its getting in there past a tube seal, or a valve cover, or a porous casting, or something like that.
In reply to Streetwiseguy:
Makes sense. The valve cover only covers the cams though. There's an aluminum "valley" where all the plugs go, that's underneath the valve cover. It's open from front to back, so why wasn't there oil anywhere else? No tubes or seals. The plug screws right into the head, and the coil-on-plug boot covers the whole thing.
I have noticed a lot of early Mazda3 and Mazda6 popping up locally with blown engines recently. Hope for you this is not your case. Actually, since I have a Mazda5 as well, I too hope its not another case of blown engine
There is still a hole where the spark plug sits, and if the valve cover gasket is leaking right above that plug hole...
In reply to Streetwiseguy:
I'd have to draw you a picture, but trust me, the spark plug hole isn't normal. The valve cover gasket is like a box in a box, the center of the head (where the plugs are) is sealed off. Ontop of that, the COP's cover the hole entrance. I mean, obviously I got oil in there somehow, but it's not like any other motor I've seen.
Javelin, i just want you to know that on my screen your user name is now a hotlink to a free credit report site.
In reply to Vigo:
Que? I don't see any ads or links anywhere on GRM *Firefox with AdBlock), but I'm pretty sure even the ones that are supposed to be there, aren't supposed to use usernames! 
It's probably an adsense widget that got into Vigos PC. As far as the Mazderp, they have a horrendous issue with oil blowby/etc due to the single worst PCV system ever invented. If you're at it, buy the tool from Ford (it's the same one they use on the Duratecs) and change that out. It's unpleasant, but will save you trouble in the long run
Is this the 2.3 you have?
I'm pretty sure there are still tube seals on there. The valley where the plugs are is just a depression in a large rectangular valve cover. It might look like it "only covers the camshafts," but that is not the case. Rock Auto says that their Victor Reinz valve cover gasket includes spark plug tube seals, so you definitely have tube seals on that car.
Yup, sounds like a simple case of leaking tube seals. They leaked on my CR-V, and they leak on pretty much every new Nissan or Infiniti that has plastic valve covers-the kicker there is that you have to buy a new cover, the seals don't come separately. 
In reply to dculberson:
Nope, mine looks different. Very similar, but clearly a different valve cover, COP setup, and wiring harness for sure. I'll go take pictures.
Parts counter said my car didn't have a PCV! Surely it must have something in the system I can replace? Or at least clean?!?
Hmmm, looks like the"inside" square on my car has gaskets. Looky:
Looks like the mini square is for cyl #1 and the medium square covers 2-4. That would make sense as to why I only have it in #1, even though the space looks open all the way. Also, no tube seals. So if this part leaks, that must be how it's getting in.
Bizarro valve cover.
Should actually be a square for #1, rectangle for #2 and #3, and another square for #4.
In reply to Swank Force One:
That is the "improved" VC gasket kit. Apparently the picture I posted is the "original" design, which presumably my first-year, original, 5 still has.
I ordered the upgraded kit, will tackle it next weekend.
Javelin wrote: In reply to Swank Force One: That is the "improved" VC gasket kit. Apparently the picture I posted is the "original" design, which presumably my first-year, original, 5 still has. I ordered the upgraded kit, will tackle it next weekend.
Ah, nice.
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