A question about sludge in a 92 Maxima

[kbohip]

My wife's car (actually my old one) is a 92 Nissan Maxima SE with 126k miles on it. This is the engine that has the troublesome VTC assemblies but that is another story. Anyway I was looking into the oil filler hole tonight and noticed that inside the valve cover area where I could see there was a brown film that had covered the area. It almost looks liked baked on oil

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The engine seems to run fine but I can't understand why the film persists. It's always had the film since I bought it used with 30k miles but I've done 3k mile OCI's ever since, using Mobil 1 the last 25k miles. I know this sounds like a dumb question, but is this sludge I'm looking at? If so would Auto-rx get rid of this?

 

[Audi Junkie]

I'm not sure if you can tell how bad it is just from the filler hole. Probally need to pop off the v/c and take a peek. Maybe while it is off just clean out the inside of the v/c a little and good-to-go. Maybe a bore scope would help? I would not worry.

 

[Matt_S]

It sounds like you're looking at varnish, not sludge. Varnish is a brownish, mostly transparent film that covers everything. You'll see it in any engine, especially where dino oil has been used. Mobil 1 can prevent it, but hasn't been shown to clean it. Sludge is a buildup of black carbon caused by severe breakdown of the oil. Auto RX should get rid of it, no matter what it is.