So I found out recently I'm burning oil like many other people on the board. My 02 SE 6 speed has 83k miles on it, so I figured this was normal. I'm currently running full synthetic and bought a 5 quart jug to keep in the trunk to top off the oil on each fill up. The first time I noticed the oil issue was when, about 1500 miles after my last oil change (and first switch to synthetic after an auto-RX phase), the oil wouldn't even show on the dipstick. It ended up taking 2 quarts to top off. My initial reaction to this was that the place I had the oil changed didn't completely fill it (I always change the oil, except when it's -9 degrees outside). Well, I got gas last night and went to top the oil off to find that after driving 288 miles, it was down about a quart, or slightly less, perhaps .9 or .85 quarts.

No, I didn't type that wrong, two hundred and eighty miles, 1 quart of oil. Oil has never collected below the car while parked, and I have never, even running the car to 6k rpms, seen smoke coming anywhere from the car, front or back. Where in sam hell is all the oil going? I know I'm not the first to consume oil, but at a rate like this? People burn far less than this and report seeing smoke... if it was leaking, wouldn't it collect somewhere??

The only thing I can think of is that it's leaking, but only while driving. Does anyone else have any input on this? All I can think to do right now is throw in cheap dino oil and keep topping it off . Any ideas or suggestions welcomed. Flame me and post a link if this has been discussed before, I don't care, I just want an answer.

 

do you have carbon deposit in your tail pipe?

 

Rydicule,

Forgive me if I am having a blonde moment (or lack of coffee). I am trying to follow this;

You change your own oil? I change mine and I measure what I get out of the car. I guess what I am wondering is, how long has this been happening? Can you absolutely verify that it is burning oil, through measuring it at next/last change? Do you have any leaks under the car? Have you checked the common issues? i.e. rear main seal/oil pan gasket?

 

welcome to the club...look at your tailpipes and the inside will be all black from the burning oil

 

I change my own oil in the summer, I refuse to get out under the car during the winter so I take it down to valvoline. This has been happening at a noticeable level ever since I switched to synthetic last January, but recently it seems to have picked up. I haven't seen any noticeable leak, however, when I do change the oil, the bottom of the pan usually has a thin layer of oil on it. I haven't started investigating leaks yet because I just assumed it was burning oil... because:


Yes, they are black as night.

But they always were, even when I was just losing a quart every 2500 miles. Sooner, do you ever see smoke coming out the back? I never have, and it seems if I was burning oil at this rate, I should smell/see it?

 

i didnt at first but now i do.
look in the rear few mirror and gun it up to redline...you will see smoke.

 

holy god, 1 qt every 300 miles?! Have you noticed significant power loss? I can't imagine you'd have much power left in that motor with compression as low as it clearly must be.

Maybe you could get a high-mile motor out of a junkyard car and start building it right (apparently nissan pistons have cheap/weak ring lands).

Sorry to hear about your motor. This must be really frustrating.

 

SEE! This is what happened to me! And people wondered how I let the engine get so low on oil it died.

 

If I were you I would get off the Synthetic oil and move to standard motor oil to start. The synthetic oil is thin compared to conventional oil and it makes it easier for the oil to pass by the rings. I have always run straight dead dino in all of my Maxima's, 94, 00 and 03. I have never had any significant oil loss between changes. That may change as my 03 approaches 60K miles, but so far, no noticeable oil loss at this point.

 

Yeah, I was planning on switching back to dino, it's also cheaper.

 

don't just switch to dino, switch to a heavier dyno. my oil consumption was significantly reduced just by going from 5w-30 to 10w-40 GTX... I used to consume about a quart every 1800 miles or so (about half an oil change interval) and now with 10w-40 my oil is still pretty much at the full line after 1K miles from when I put in the heavier grade. I'm almost tempted to go synthetic on my next change just to see what happens.

 

oil level has nothing to do with compression or power loss

 

total BS
if the synthetic is is some VISCOSITY...the "thickness" is the same.
i changed back to conventional when the dealership told me that and i still have the problem.

the problem is bad rings

 

My power has never waivered. Of course, now knowing that USING that power may be a bit more expensive than just gas...

 

True, but conventional oil IS cheaper to burn away

 

So if both of my tailpipes are black as night, AND I have a slight timing chain tick.......I just got it up the *** by my VQ???

 

Those are just signs of oil burning. But the first thing to check before determining if you're burning oil is...



the oil. You haven't gotten it up the *** until you're actually losing oil.

 

Clearly oil is getting passed the rings somehow. You won't have in-spec compression on a cylinder that is allowing oil to pass through...

 

Viscosity measures a fluid's resistance to deform under stress....A highly viscous fluid resists deformation moreso than one with a low viscosity. Conventional oil (with a higher viscosity) will resist getting through the rings more than synthetic oil with less viscosity...shear fluid mechanics.

 

synthetic oil doesnt cause the problem...it might make you more aware of the problem.

 

Did I say that was the cause? I was just going against what you said, which was that switching to dino oil will make no difference. Will it completely stop oil from getting past the rings? No. But it will slow it down.

 

i understand what you are saying but it didnt slow my oil loss.

 

Well there are so many factors involved that it's possible to go almost un-noticed. Throttle use, average temp., the condition of the rings, etc.

But I digress. Just figured I'd get some facts straight

 

Another oil loss story....

Never ever trust Ward's!!!


http://wardsauto.com/reports/2007/te...ssan_3-5L_V-6/

 

well i still agree that the engine is amazing....its just the rings that are bad

 

Looks like you notice the oil loss after the Auto RX and the switch to synthetic. Not sure if either has anything to do with the oil loss, but I would go back to the previous oil to see what happens.

 

Visosity is a material's resistance to flow!

Has anyone on this forum changed rings that has had the oil burning issue in their 3.5??? Everyone is wondering and pondering, bickering and fighting about what it could be.
It's very obvious that it seems to be rings.

 

I agree, the oil level probably has little to do with compression. However, if the rings or ring lands are bad enough to let one quart of blow-by occur within a 300 mile period the motor is certainly experiencing lower compression levels in the combustion chamber than it was when it was working properly.

Most people will diagnose a bad cylinder (one that contains a piston with bad rings) by doing a compression test. You'll generally expect to see the PSI of that cylinder lower than the other cylinders. So say the motor that rolls out of the factory runs 200PSI +/- 10psi on all slugs. At 0 PSI you'd expect a cylinder to make no power (and probably long before that). If you've got a slug (or several) that are down 30 or 40 PSI, you can be sure they're not producing as much power as they once were.

 

i already told you it was the rings

people have checked the rings on other 3.5s and they were bad.

 

ive performed a compression test on my engine - passed
performed a leak down test - 3 cylinders failed

 

So why all the oil burning/loss threads and posts when the problem IS identified?
Seems that you have 2 options:
1-leave it and keep adding oil
2-tear motor down & replace rings

 

Makes sense.


What people don't realize is that a ring set can be good at sealing combustion pressure in and still fail at oil control. Oil loss generally won't occur under power because the rings actually use combustion pressure to press out against the cylinder wall harder; the ring tension on its own is nowhere near enough to seal properly. With that said, compression pressure (and subsequently, power) can go unaffected while a motor comsumes oil. It is when the rings are relatively unloaded during cruising or coasting from high RPM that the most oil loss can occur with bad rings. Furthermore, the rings that are there primarily for oil control don't affect compression much. The oil ring and 2nd compression ring are the 2 that take care of keeping the oil out of the combustion chamber while the 1st compression ring is the one that affects compression the most with the 2nd ring being a secondary compression seal as well. Now there are cases where the rings are bad enough to bleed excessive pressure off AND fail at oil control, of course. But there are some cases where oil burning isn't accompanied by a power loss and won't be detectable by a compression test.

 

i will be rebuilding my engine when i get back to OK next year.
ive already done all the research.
thread in all motor forum

 

Sweet, good luck with that. I'm sure you'll be happy with no more oil loss. What else are you doin to it while its apart???

 

since its already gonna be open, probably new pistons and connecting rods. maybe even cams.

 

Well I suppose there are some motors where only the oil control ring fails, but I think that's probably highly irregular. Especially with a motor that's chucking a quart every 300 miles I would think you'd have to see a compression loss somewhere. For motors of over 1000/qt I can see how it would have less effect.

 

It never ceases to amaze me that the VQ35 somehow continues to make Ward's best engines list.....

Also, a guy I work with is having the same problems with his 350z, which has something like 25k miles on it. He says he has to add a quart every other fillup and Nissan can't/won't fix the problem.

 

Inferior rings ≠ inferior design. There are a HOST of improvements the VQ35 made over the 3.0. It just so happens that the rings are crap. Unfortunate really...


Rings and displacement aside the VQ35 is a flat out superior motor, IMO.

 

Last time I looked in a Haynes, it reccomended running conventional oil on older/higher milage engines to be sure. I don't think there's any reason to dispute Ward's process. they don't test engines for 50-80k to come up with their results, and the fact is, the VQ constantly wins for superior NVH and power delivery. The first year that honda intrduced their 3.2L V6 with 270hp, they yawned at it compared to the VQ because it delivered it's power in a sterile manner. no passion. I can safely say that I likely would not have bought the maxima ever if this car did not speak to me through it's engine. so 'eh' the rings suck. some way more than others. get a full ring set and get them Cryo'd, then put in. I'll apologize if you didn't buy the extended warranty, but I'm at 125k and while I know I burn oil, I've never had a service tech go "Yikes", so I must be doing SOMETHING right.

 

Has anyone considered a VQ35 to VQ30 swap?