Hey guys, I have a 2004 G35 Coupe. I've done a ton of work to this car and know it pretty much inside and out. I've posted on other forums, but can't seem to get a good answer. I know quite a few of them have oil consumption issues, and while mine always burned some oil it didn't get bad until recently....

Anyways here's the deal... at about 85k I decided to swap out my Spark Plugs. I used NGK Iridium plugs. Long story short one of the coil packs went bad. Took me a little while to diagnose and had to eventually take it to a mechanic. Throughout all the testing, fuel had leaked into the CAT and combusted, causing the CEL to come on. So I had to get a new coil pack, and replace my CATS. Ended up getting the Berk HFC which work great.

Ever since then, my oil consumption sky rocketed. I drive about 1000 miles a month, and probably burn 2-3 quarts in 1000 miles. I am thinking something else may have been damaged internally. There is no leaking, no drips anywhere, and no blue smoke. Sometimes I can hear a low rattle during acceleration (it's louder if the oil is low, thats how I know when to add oil) so I am thinking it's possible that the Cam Shaft Positioning Sensor may be doing some craziness with the Cam Shaft.

I've tried doing 2 seafoam treatments to the oil (everyone has their opinion on oil additives, but I heard some good things on the cleaning and lubricating properties of seafoam, so I thought I would give it a try)

Thoughts? What could have been damaged? What are some areas I can start diagnosing?

 

Oh and by the way, car runs great, and no noticeable loss of acceleration. Just eating a ton of oil!!!!


I'm using 5w-30 synthetic. Some people have recommended switching to dino or a heavier weight oil, but I think this is more of a patch job, then a real solution.

 

I had this problem in my altima before and it ended up being a rod. The rod dam near pushed through before I caught it. Hopefully this won't be the case for you.

 

If you have a lot of bolt-ons, chances are the HFCs are the cause of this. Over the years, I've read numerous cases of OC increasing dramatically once HFCs or TPs are added. The owners put the OEM cats back on and the issue goes away. The fact that this issue popped up right after installing the HFCs tells me the HFCs are likely culprit.

 

I am a bit confused? How could HFC effect oil consumption? There are tons of G's out there that have HFC. Also this is exhaust, how could the exhaust system effect the rate of oil consumption? Doesn't seem to make logical sense... care to enlighten me?


A rod would really suck....
I was thinking perhaps the rings or something else was damaged during the misfire. I've read some information about the valve covers going bad, but that would cause an actual leak where I would see oil on my driveway, which is not the case....

Thoughts?