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Discussion Starter · #1 ·
Hello Gents - as some of you may remember, I have been working to breathe life back into a 2009 G8 GT I purchased with approx 100K on the odo (brakes, rotors, shocks, struts, springs, radiator, etc...). The car seems to run fine, but noticed a slight miss at idle from time to time. Pulled the plugs and swapped out plugs and wires this morning, and the pic below is the condition of the plugs. As you can see, heavy oil on half the plugs (threads), and the other half are dry but somewhat corroded. Lastly, the car did have DOD failure at 95K, and the invoice from the local dealership in Austin was $7,500 to repair the damage. Anyway, if someone would give a look an offer up an opinion that would be much appreciated. Added arrow from "front to back" and DS/PS (driver's side /passenger side) so you can see which cylinders are associated with the oil on threads.
184946

Thanks guys!
 

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Oil could be coming from a leaking valve cover gasket, spark plug o-ring/ tube seal and two other possibilities which don't seem likely at this juncture. Weight and blend of oil you're using? Brand of gasoline? It's quite possible the spark plugs have never been replaced or were changed awhile ago.
 

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I’m sure when the shop did the repairs they just pulled the heads and set them aside. Then valve stem seals need replacing. I recently replaced valve springs on mine and most of the seals wouldn’t hold the valve up. That’s at 54k miles. (87k km). Are you planning future mods? Best to upgrade the springs when changing the seals. If it was an external oil dripping down on the plugs I would expect the silver nut portion of the plug to be oil covered too.
 

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Discussion Starter · #4 ·
Hello Pony Man & GT Drew -
Thanks for the quick reply, and valve stem seals are what I was initially thinking (but hoping wasn't the issue). Did the seals & springs upgrade on the GTO - but that was when I had a bit more time on my hands. PonyMan - always run 91 without ethanol (usually from BP). Since I purchased I've always used Castrol 5W-30 full syn. And lastly, hard to believe that the dealership wouldn't have replaced the plugs when charging $7,500 - but based upon the condition they appear to be the original plugs. Thanks guys - really appreciate you both taking the time to reply!
 

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You're welcome. Would change the spark plugs and check their condition after some time has elapsed. The oil leak isn't excessive and have seen far worse, but definitely worth noting for future reference. Am not a proponent of those supposed oil leak stops which if they work are merely prolonging the inevitable. Personally use Castrol GTX high mileage which has "seal conditioners to help reduce leaks" albeit not for that particular reason.
 

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Those plugs are either very old, of not original but definitely not 5k miles unless you have serious engine issues. My first thought is valve stem seals like previously mentioned. Not a difficult job but worth doing especially with 100k on the odo. Any visible oil leaks from the valve covers or pcv system? My guess is the dealer did not do plugs at the same time as repairing and you mostly paid a huge premium for dealership labor which is usually close to double what mom and pop shop would charge. For example, they're charged you for recovering refrigerant and removing the condenser because that's what "the book" says but they probably didn't do all that.
 

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Discussion Starter · #7 ·
I agree with you that the dealership charges a premium - but that was paid by the couple that I purchased the car from. They provided the receipt for the repair, which was for $7,500 and was done 2,000 miles before I purchased the car. And yes, I don't think the dealership changed the plugs based on the condition of the tip and electrode on each plug.
 

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Better question is where did the oil come from? Plugs were not your issue, it’s the oil.
The plugs need changing, but you haven’t found the source of the oil. Is the intake manifold full of oil from the PCV system?
 

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Discussion Starter · #9 ·
Haven't checked inside the intake yet, but inside of the throttle body was clean when I installed the Roto-Fab a month or so ago. I don't have a catch can on the G8 like I have on the GTO, so I'll check the intake - thanks for the input!
Better question is where did the oil come from? Plugs were not your issue, it’s the oil.
The plugs need changing, but you haven’t found the source of the oil. Is the intake manifold full of oil from the PCV system?
 

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Lone Star State
2009 Pontiac G8 GXP
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Haven't checked inside the intake yet, but inside of the throttle body was clean when I installed the Roto-Fab a month or so ago. I don't have a catch can on the G8 like I have on the GTO, so I'll check the intake - thanks for the input!
Since you say you don't have an oil catch can, and the fact that you have 100K on the engine, you might be experiencing excessive piston ring blow-by. Thus increasing the need for a catch can. Does it smoke a little at cold startup in the mornings; a sign of oil leaking down the valve stem seals at night.

I will try to post a video later today showing the importance of a catch can. I have Holley valve covers and each one has a vent tube. I had the passenger side running into a catch can, but the drivers side valve cover vent tube was feeding directly into the supercharger inlet. I will show you soon what the result was after only 4K miles of moderate driving. More to come.
 

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Lone Star State
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Here's a video link showing the result of improper plumbing for a catch can.

And here's a video link of a noisy front coupler on a Magnuson Heartbeat Supercharger.
 

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Discussion Starter · #12 ·
Thanks for the videos, and will definitely look into adding a catch can on the G8.
 

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Also look into the mod of drilling some extra drain holes in the drivers side cover. It can keep from getting oil in the PCV line in the first place.
 

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Discussion Starter · #14 ·
Thanks GT Drew - had not heard of this and will definitely search this topic! Thanks again -
 
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