I am having a very interesting problem.

I have 2000 SE 20th aniv. with under 5000 miles.

When I took the car in for it's first service at 3750 I got a call saying the air filter needed to be changed. Huh? I asked them to keep the filter for me to look at.

When I got back to the dealer the air filter had a bunch of oil blow by on it. It had not soaked through to the other side, but it did get to the bottom of the folds. It was very localized toward the bottom left of the filter in about a 3 inch circle. After seeing how the filter is placed in the car it lines up very well with air flow.

Anyways, when I told them that if the oil on the filter was cause for it to be changed at 3750 then there was a bigger problem, and the car needed a full diagnostic. Well all of sudden I got themn back tracking. They bring out a different mechanic to look at it (supposedly their Nissan expert). He goes on to say. It's not a problem the air filter should not have been changed and that what we were seeing is "normal". I didn't argue then since they didn't charge me for the filter, but I am very skeptical that it is "normal".

So I have now put another 600-800 miles on the car and I am noticing the same thing. An oil circle is starting to develop in the same place on the brand new oil filter. I have never seen this on my other cars at all.

My first thought was maybe they had overfilled the oil which was causing the blowby. However I checked the oil and it is slight below the fill line, right were it should be. I have not used synthetics so I don't think that is the cause of the blowby either.

If anyone can verify that this is "normal" or not I would really appreciate it. I want to go back at my next service much more informed. If no one else is seeing this, I will ask them to call the tech line and run a full diagnostics. I am very worried that this is going to cause a big issue as I get more miles on the car.

Other than this the car runs beautifully.

Thanks for you help in advance and sorry about the long post. Just thought I should provide as much info as possible.

 

All I can offer is this. I swapped my stock filter for a K&N at about 4,000 miles. There was no such oil marks on my filter. In fact, I still have it and just took it out to confirm. No such pattern at all.

 

Yeah i have 35000 on my car and I have never seen that problem either. I changed my filter to the stillen high flow, but when we took out the filter i didnt' notice oil either

 

it was dark on one side, light on the other.. It was not saturated with oil anywhere on it. (same for my pathfinder as well, same mileage as max)

 

I'm no Nissan Mechanic - Thank God! But I see no reason at all how this could possibly happen - oil in the air filter. Air flows from the small intake under the hood, through the air box/filter, and up into the TB. The TB can't put air OUT, the intake is a "one way street". Please don't get me wrong, I'm sure something is making the filter look strange. But my guess is it's moisture coming in the intake and collecting dirt that looks like an oily film. I have the K&N panel and do notice a "round circle" of dirt where the air flow is focused.

 

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Don't forget we have that VC hose that goes into the intake to refeed for emissions..it has oil.