I couldn't answer that, I don't know how often they fail on anyone else's cars.You can get a set of Victor Reinz valve cover gaskets, which I used for my G, Audi, and Rav 4. They make a good quality part and it's pretty cheap. Mine were brittle, hard, and could be broken easily after being on there for 10 years and I only had one leaking into the spark plug galley.

 

boca, failing vc gaskets are pretty uncommon on a stock DE motor. The seals, not so much. We just wish there were more replacement options for the seals, it's a shame R&D Factory couldn't stick around. Seems like they had a corner on the market for these........

 

Dropped the 06 G35 at my regular Infiniti dealership to evaluate the oil smell and the cost to repair. I asked my service writer who I know well, to do a thorough inspection of EVERYTHING under the car that might need attention now or in the near future before I go forward to correct the suspected oil leak. Turns out this is the report:

1) Both valve covers are indeed leaking and need replacement. Cost: Close to $1700. I was told the parts were $900 which made no sense. He started talking about items other than the Valve Covers and Valve cover gaskets that were necessary but still didn't come close to $900. I told him the parts should cost no more than $500 tops! He did return a call with a price or $1300+ minus some gaskets.
2) The rear main was leaking......which I did notice that last time the car was on the lift. This troubled me as it is not any easy fix.... and although it's not yet dripping on the ground can only get worse and will be quite expensive.
3) Two steering knuckle boots are ripped and although there are no noises and they are tight, it still will need to be addressed down the road.

Bottom line is, even though my girlfriend is the original owner with 85,000 miles,and a beautiful body condition.... it is probably practical to abandon ship and sell the car at this time. We will be entertaining options for other new, used, and leased cars over the weekend. Sometimes, it no longer pays to put good money to bad. End of story.

 

Why would I have to replace the valve cover? It seems like everything I'm reading talks about replacing the valve cover too.

 

The spark plug holes are a molded gasket in the valve covers. It slides over the spark plug tubes and makes a seal. They shrink over time and heat cycling and leak oil into the spark plug tubes. They are built into the covers so you cannot replace them. You know they are leaking bad if you have your car in a quiet area idling and hear it miss every once in awhile. When the oil fills the tube enough to get the spark plugs wet they will ground out instead of fire every once in awhile. The lower cover gaskets are replaceable.

I have done this on 2x 04'-06' VQ35DE cars and 1x 07'-08' VQ35HR car and so far permanently fixes the leaks. Only costs about $50 in parts to do.

Pull upper intake, pull valve covers, put paper towels in all 6 intake holes so you don't drop anything down there, wash the valve covers and then carb clean them really really good, use a scotch brite green pad and clean the spark plug tube gaskets then cab clean again, use the scotch brite pad on the head surface until completely clean and carb clean off, Use scotch brite pad on top of the spark plug tubes and then carb clean. Make sure all gasket surfaces are completely clean with out any oil or RTV will not stick. But Permatex Ultra Grey RTV silicone. Buy Fel Pro valve cover gaskets. Clean gaskets with carb cleaner to remove and mold release on them. Use the ultra grey silicone in about 8 spots so the gaskets will stick to the valve covers, let it tack up and partially dry for 1-2 hours. This will make your life much easier because they can fall out while trying to install and then it will leak everywhere and you will have to do it again. Silicone the head surface where the gasket mates and make sure you use a bunch on the front corners buy the VTC area. Silicone the spark plug tube gaskets and wipe a thin layer on the spark plug tubes. Reassemble.

I have re used the valve covers on 3 cars this way and not had 1 leak yet, not even on my 10psi boosted car. Be aware this is a permanent fix and if you have to remove the cover it will probably crack since they will be stuck down pretty good and the covers are very old. But it will allow you to get another 80-120k miles without buying valve covers.

 

Interesting idea. Thanks for the detailed share.

 

How does scrubbing down the surfaces of the spark plug tube seals prevent future leaking? Most of the time these seals are leaking because they've shrunk due to the heat cycling. I'm curious as to how your method actually solves the oil leak problem. Reason is, I just replaced my valve cover gaskets, and I didn't clean off the old oil on the spark plug tubes which I'm sure prevented a good seal. I opened up my coil packs on each spark plug a month after installing the brand new covers... EVERY spark plug tube is filled with out. And when I say filled, I mean I literally can't see the spark plugs because theyre below the oil level in the tube.

If this works, its worth a shot. Sounds like an EZPZ fix.

 

After you use the scotch brite pad on the spark plug tubes and tube seals in the covers then carb clean everything really good. Use a thin layer of RTV on the seals, use a thin layer of RTV on the spark plug tubes. Then re install the covers. They will be sealed for good, like I said they are boost proof at that point.

It's a good way to seal them but they are really hard to get off after the RTV sets. Being a composite type valve cover and old & brittle they probably won't come off without damaging them if sealed this way.