I have a 2005 G35 sport coupe with 115,000 miles on it. Just changed the plugs and noticed oil on the 2 plugs closest to the firewall . One on the drivers side and 1 on the passenger side. I had noticed an oil smell for a while and couldn't figure out what it was. Now I know. The car is running fine but I seem to be getting worse gas mileage than before. Is this because of the oil? If I continue to drive the car the way it is will I damage anything engine wise and just put up with the smell and worse gas mileage or should I have this taken care of right away. What am I looking at price wise and what exactly will I have to have done?

 

Is it on the spark side of the plug, or the side where the boot plugs into it? If it's on the boot side, no worries. Only new valve covers will fix it(built in gaskets). If it's on the spark side, then you have issues somewhere(valve seal)

 

I think you have those backwards, wording is confusing.

 

It's right. Lol. If it's on the part that actually sparks, it's an internal problem. If it's on the ceramic side, it's the gasket

 

I believe it's on the spark side, the side that's threaded. That's where I saw the oil. The electrode side. What will happen if I continue to drive it this way? What kind of work will I need to have done to fix the problem?

 

Get a compression test done. If that checks out, it's not a piston ring. My guess after that would be a valve stem seal or bent valve. Is there a decent amount of noise in the valvetrain? If so, bent valve, if not, seal. Not very expensive to fix. Piston ring, expensive to fix

 

what weight oil are you using? many here with high mileage still very light oil.. I would try 10W40 synthetic..( this does not emit blue smoke like the dinosaur stuff)