Hey guys

My car (06 G35x) now has 156K miles on it. I changed the plugs back at 120K miles.

Just recently my mpg has gone to s***. Car sometimes shakes a little when idling not too bad though. I decided to pull the plugs and check them out after having 36K miles on them.



What I saw surprised me. I was expecting to see plugs that looked sort of brand new since they only had 36K miles. But the plugs look almost as bad as when I changed them at 120K miles

Things worth noting:

1. I always use premium 93 octane
2. I noticed a pasty gray substance on the plugs. Especially at the base where the plug meets with the coil pack. You will notice it in the pictures. It was not anti seize btw as I did not use this when I did the plugs.
3. Spark plug gap increased compared to brand new.
4. I also noticed white deposits on the tip of the plugs.
5. There was NO motor oil on the spark plug or coil pack. So im going to rule out valve cover gaskets.
6. I do sometimes use the Chevron Fuel System cleaner. But very rarely.
7. I have noticed I burn about 1 quart of oil every 3000 miles.
8. These are the NGK double platinum laser plugs aka the OEM


Thanks!!

 

Those look to be somewhere in the middle of normal, and overheating?

http://ngksparkplugs.com/tech_suppor...qs/faqread.asp

Based on that one pic, nothing jumps out at me as being a bad plug.