Hi all, so I noticed my g35 had been consuming more oil than what I thought was normal.

I did a spark plug change and cylinder 4 had a pretty nasty plug. Seemed like it had chunks of burnt oil (or so what I believe to be oil, didn't look like carbon to me).

Read around the forum here, and some members commented that the valve covers might need replacement or spark plug tubes/seals. Just wanted to get an opinion from y'all as I'm fairly new to having this car and I'm not all that "trained" in regards to knowing exactly what my spark plug is telling me.

Thank you in advance and any help is appreciated.

 

doesn't look like a valve cover issue. If it were, you would have oil on the top part of the plug nit the bottom that's in the engine combustion chamber. looks like either oil or un-combusted fuel left on the plug. any idle issues?

 

Ohh I see. Yea didn't have any sort of oil on top part of plug. Just the build up that's on photos. And it actually seems to idle pretty smooth at least to me. No rough idling or fluctuations. Would you happen to know what my possible culprit might be? Thanks

 

In most cases its either bad fuel or oil on the plug. If that were the case I would imagine that all cylinders would show similar results. How many miles do you do you have? do you have any oil consumption issues?

Id try and do a compression test for assurance that its not your piston rings

 

Yea that would make sense for all plugs. And it had roughly 131k miles. It definitely has some oil consumption. That's the reason why I started poking around. I bought it at about 127k miles so I would say piston rings could be a possibility.

But yea compression test sounds like a good idea. I will keep y'all updated if I get a chance to do it this weekend or sooner. Thanks for the replies!

 

Which cylinder is the smoked plug out of?
That does look like oil in the cylinder, but not from the valve cover. I'd say it's from the intake. There are two oil vapor lines going into the intake. One in the back that goes into the intake tube and one in the front that goes into the plenum.
You might wanna pull the top plenum off and see if you have any oil in there.
If you do, you need to install a catch can to avoid oil vapor getting inside the cylinders through the intake valves and smoking your plugs.

 

The bad plug was in cylinder 4 (middle one on driver side)
And thanks for the recommendation, I actually hadn't heard of oil vapor being an issue so I'll look into that this weekend. Correct me if I'm wrong, but is the like you're referring to connected to the valve cover? (I believe it's the one connected to PCV valve) Either way, I'll probably run a compression test and take off the plenum as you suggested. How worries should I be if I have to install a catch can? Are there other parts that could've possibly been damaged as well? Thanks for all the input.

 

One that runs from PCV valve and another on the top right corner of the engine under the throttle body.
There are two lines all together.

What oil vapor in the intake can do is hinder your performance, damage plugs, damage cats (clog them).

 

I had a similar problem, but all my plugs were like this. I changed the plugs around 5k miles ago and I noticed the burnt oil and I noticed some residue on the threads when I pulled a couple. I also noticed blackness beyond exhaust in my intake. So I prolly need a catch can valve cover seals and I was thinking about replacing the pistons with bigger ones and having the cylinders honed but I'm not sure how big I should go. Maybe 96mm? Any suggestions??