Excessive oil consumption in VQ 35 engine? R50 Pathy (followup)

[Martinjmpr]

So this is a followup to a thread I posted in January:
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http://forum.expeditionportal.com/threads/167532-VQ35-engine-oil-level-question-(R50-Pathfinder-)
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For those who don't want to read it, vehicle is a 2002 R50 Pathfinder, 5 speed, VQ35 engine with ~ 121,000 miles on it (it's cherry!) I got it in September to be my DD and "city car" (so I don't have to put miles on my Suburban.)
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Back in January I noticed my oil was low by over a quart. Added oil and brought it up to showing full on the dipstick. This would have been about 4 - 5 weeks ago.
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About a week ago, the Pathy threw a CEL. I don't have a Scangauge or Ultragauge (yet) so I ignored it. Previous owner told me sometimes the CEL would go on with no change in performance, I figured it was a sensor or something, no big deal.
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Last night, with the low fuel light on I decided to fill it with gas. As usual, I checked the oil (after it had been sitting on a level surface, engine shut off, for maybe 5 minutes.) Dip stick was once again BONE DRY.
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So I drove to Wally World and bought 3 quarts of 5w30. Put in the first quart - still no oil on the dipstick. Put in the 2nd quart, now it was showing full.
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Closed everything up (the 3rd quart is still sitting in the back of my Pathy.) Went to start - lo and behold, the CEL was off!
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So a couple of questions:
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First of all, have there been any reports of excessive oil consumption with the 3.5? My old Montero with the 3.0 V6 would burn about 1 quart of oil every 1,000 miles but it also had noticeable blue smoke coming out of the exhaust. I park in a driveway and if I was leaking oil anywhere, I would know it (actually I would catch hell from my wife because we just moved into a new-to-us home.) If it's not leaking, it must be burning, yes? I mean, what else could account for the oil loss? Keep in mind that the truck was full of oil as recently as January and by the end of February it was down by 2 quarts!
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Second, is it normal for Nissans to throw a CEL when they're low on oil? I've never known another vehicle to do that. I mean, I'm glad the CEL went off after I added oil, and I guess it's nice that low oil level will throw a CEL and give me something to check out, but I've just never heard of low oil, by itself, causing a CEL.
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I should point out that through all of this, every aspect of performance, power, fuel economy, etc, has been completely unchanged. MPG in mixed city and urban highway driving remains around 17 - 17.5. That's running regular 85 octane E10. I did about 3 tanks of 91 octane with absolutely no difference in performance or MPG so I went back to regular.
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Thanks in advance! :ylsmoke:

 

[wreckdiver1321]

I also have a VQ series engine, granted it's the 4.0, not the 3.5, but a lot of the engine is more or less the same. I'm on 173k and still don't burn or lose a drop of oil.

I'd be concerned with that much oil loss. How many miles have you done since you last refilled the oil? If it's not leaking somewhere, then you kind of have to be burning it. I can't think of anywhere else it could run off to. Have you checked underneath the vehicle for wet spots? Driving has a tendency to make the oil streak, and sometimes it drips where it accumulates and doesn't make it to the ground. That said I'd be really surprised that if there was a leak, it wouldn't be making it to the ground, especially with that much loss.

As for the CEL, it may have some sort of sensor for that. But wouldn't that be the purpose of the oil pressure light/sensor?

 

[toyick]

The 3.5's in the cars from that same era have been known to drink oil like that... That is not a good thing though...
I used to be a huge VQ fan in the maximas, but the earlier era, vq30 was a great motor...Nissan did something with the 3.5s that weren't quite as reliable as the earlier models.

 

[Martinjmpr]

Hmmm...a quick Google search seems to have turned up lots of VQ35 engines with excess oil consumption. Am I the only one here experiencing this?

 

[Martinjmpr]

So apparently this is a fairly serious issue that will sooner or later lead to engine failure.
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It's a bit of a dilemma to me. I could:
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1. Sell the Pathy, it's in great shape, has brand new tires and only 121k on the clock. Basically "kick the can" and make it someone else's problem.
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2. Continue driving it until it needs serious work and then reassess whether I want to fix it or get rid of it. Since it's "just" a DD, it's not likely to leave me stranded anyplace far from home.
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3. Try to fix the issue. The problem I can foresee here is that the various web sites don't seem to indicate one "known" flaw that's causing this. Instead there are a whole bunch of theories with different possible "solutions", many of which don't seem to have any effect.
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At this point I'm leaning towards choice no. 2: Just continue to drive it until and unless it needs work.
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And you know what sucks is that I really LIKE this R50! It's comfortable, fun to drive, powerful for its size, and I LOVE the way it looks! It handles well, does great in the snow (now that I have decent tires on it) and it even has a sunroof, which I've never had before. I like everything about it but the excess oil consumption makes me think its days are numbered.

 

[toyick]

So apparently this is a fairly serious issue that will sooner or later lead to engine failure.
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It's a bit of a dilemma to me. I could:
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1. Sell the Pathy, it's in great shape, has brand new tires and only 121k on the clock. Basically "kick the can" and make it someone else's problem.
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2. Continue driving it until it needs serious work and then reassess whether I want to fix it or get rid of it. Since it's "just" a DD, it's not likely to leave me stranded anyplace far from home.
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3. Try to fix the issue. The problem I can foresee here is that the various web sites don't seem to indicate one "known" flaw that's causing this. Instead there are a whole bunch of theories with different possible "solutions", many of which don't seem to have any effect.
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At this point I'm leaning towards choice no. 2: Just continue to drive it until and unless it needs work.
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And you know what sucks is that I really LIKE this R50! It's comfortable, fun to drive, powerful for its size, and I LOVE the way it looks! It handles well, does great in the snow (now that I have decent tires on it) and it even has a sunroof, which I've never had before. I like everything about it but the excess oil consumption makes me think its days are numbered.

as of right now i wouldnt think to hard on the fact...as long as your dont have a water/oil mixture its being burnt, and if you dont see blue smoke then i wouldn't really worry about it....until you see actual smoke or it effects a smog check.

 

[stioc]

Yeah that's a tough decision. I have the same engine (and earlier one at that) and don't have any oil burning issues. I've done trips to Utah and CO from SoCal without needing a drop of oil (nothing significant) and I have 146k miles on mine. Unfortunately though that's the thing with buying used cars, you never know what you've got until you find out. However if you really like it as you say you do then toss another engine in it when the time comes as long as everything else is worth the expense (in good condition otherwise which it sounds like it is). I know of someone who was sentimentally attached to a car that saw 1 engine swap (used engines) and one transmission swap but the person was happy with that with the car approaching 260k miles. In my case if the truck needed an engine or transmission I'll be replacing those parts but not parting with the truck...but then I have way too much invested in the truck besides the money (some blood lots of sweat and tears...).

How many miles before it's down a quart? Is it leaking oil at all? is the tailpipe wet/oily?

 

[Martinjmpr]

Yeah that's a tough decision. I have the same engine (and earlier one at that) and don't have any oil burning issues. I've done trips to Utah and CO from SoCal without needing a drop of oil (nothing significant) and I have 146k miles on mine. Unfortunately though that's the thing with buying used cars, you never know what you've got until you find out. However if you really like it as you say you do then toss another engine in it when the time comes as long as everything else is worth the expense (in good condition otherwise which it sounds like it is). I know of someone who was sentimentally attached to a car that saw 1 engine swap (used engines) and one transmission swap but the person was happy with that with the car approaching 260k miles. In my case if the truck needed an engine or transmission I'll be replacing those parts but not parting with the truck...but then I have way too much invested in the truck besides the money (some blood lots of sweat and tears...).
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How many miles before it's down a quart? Is it leaking oil at all? is the tailpipe wet/oily?

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I typically fill up at 280 - 300 miles in town and that was the only time I checked the oil - at that point it was 2 quarts down. Now that I'm aware of the problem I'll check the oil more frequently.
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And no, it's not leaking oil, not a drop. Nor is there any smoking or signs that you would typically expect to see if the rings were shot (I owned a car that would burn oil from the rings, it left a gigantic smoke cloud every time I started it up in the morning - I know the neighbors must have hated me!)
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The oil itself is not a huge issue to me, it's deciding whether or not the oil consumption indicates that my engine's days are numbered.

 

[stioc]

So it's entirely possible that whenever someone changed the oil last never filled it up to the proper level? If it's not leaking nor burning oil that's the only option left that I can think of and thus there's nothing wrong with the engine itself. I'm surprised the oil pressure light didn't come on, does it come on when you set the key to ignition?

 

[Martinjmpr]

So it's entirely possible that whenever someone changed the oil last never filled it up to the proper level? If it's not leaking nor burning oil that's the only option left that I can think of and thus there's nothing wrong with the engine itself. I'm surprised the oil pressure light didn't come on, does it come on when you set the key to ignition?

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No, I topped it off with oil a few weeks before this happened.
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UPDATE: Filled the tank again on Monday, there was oil on the dipstick but it was low, so I added 1/2 qt. Will continue to monitor at 150 - 250 mile intervals (it normally needs gas around 260 miles anyway.) MPG seems consistent around 17.7, which is pretty respectable for the mostly suburban driving I do.

 

[Allof75]

Oil burning seems relatively common on this engine family, as far as I know there are some people who continue to add oil, but at some point it may lead to all sorts of serious issues for that particular motor. That said, you might be able to find a low mileage motor in a wrecker's somewhere at that time.

I think you would be best suited to check the oil frequently, and check underneath your skidplate/splashshield near the power steering pump. If there's oil there you may have an oil cooler leak, mine did and the oring was $11 from Nissan.