I have a 2005 Nissan Murano with 130,000 miles on it. I have performed every single recommended maintenance at the proper time, including oil changes and tire rotations, and have records of each (done at the same dealership). I love the car and have not had a single problem with it until just very recently. A couple of months ago, we had to replace the catalytic converter. The mechanic told me that it wasn't really bad yet, but it would be a good idea to replace it now ... so I did.

Shortly thereafter, just before my scheduled oil change, my oil light came on. I'm not sure if this was the very next oil change after changing the part, or if it was a few changes later ... I could look at my records, but I don't have them with me at the moment. Anyway, we checked the oil and had to put 2 quarts in it. The next morning I took the Armada to work and when my husband checked the oil, he had to put in another quart in it. There is no sign of leaking anywhere, on the driveway, or under the engine. Two days later, I had the oil changed at the dealership. At that time, the mechanic told me that the oil was low. He changed the oil and told me to check it every few hundred miles to make sure it stays full.

I’ve been checking the oil regularly and have had to put in 2 quarts in the past month or so. Although I haven’t noticed any smoke from burning oil, my friend was behind me yesterday and told me that I had a little black smoke coming out of my exhaust when I passed another vehicle.

The dealership told me that when the catalytic converter goes bad, the engine sucks up little pieces of metal and this is most likely what is causing it to now burn oil. Have you come across this with other Muranos? Is there a chance it could be something else? I still owe $13,700 on the car (another 2 years of payments), and really don’t want to get rid of it unless it makes more sense to do so.

Any advice? Thanks in advance!!!

It looks like the new catalytic converter is not working properly. If theres no sign of oil leak, then it has to be the only reason. I should try re-installing the catalytic converter. If the problem still continues, Change it to another one.
Don't worry, your car is just fine, Muranos are the one of the most stable cars around. The problem is , if anything is a little missmatched, it starts to act up, just like Intel motherboards!!
I hope you get your car fixed.

Converter in in exhaust and would have nothing to do with burning oil. All a converter does is reburn exhaust gasses. It has a catalyst in it that reacts with heat and exhaust and gets very very hot and burns off any unburned gasoline.

No way any metal from this can go against the force of exhaust and enter the combustion chamber.

Engines burn oil due to either warn out rings or valve guides or both. These are the only 2 areas where oil can enter the combustion chamber.

Sometimes sludge can cause rings on the pistons to freez up and this can cause issues. I recommend using 100% synthetic oil and do oil change every 5000. If you are having issues now and you are not using pure synthetic, not blend, then switch and see if it cleans up the engine. Synthetic is superior for cleaning and preventing sludge. Also dyno oils have a problem of varnish deposits. Pull your dip stick and wipe it. if dip stick is varnished brown then you have been running conventional oil. Same deposits get on sides of pistons and make rings stick. A car that has only 100% synthetic will never have this varnish. I have taken apart engines and witnessed this myself.

Try running 5w30 synthetic for a while to let it clean it up. then switch to 10w40 depending on how cool it gets in your area of course.

Thanks for the replies! The mechanic told me that when the catalytic converter goes bad, little tiny pieces of metal can get sucked in and scar the inside of the [whatever it goes into ... sorry, I'm a girl...] and that is what causes it to burn oil.

I would assume that the dealership uses synthetic oil, though I'm not sure. We have had every oil change done at the same dealership.

If we had to change the converter again, wouldn't that be really expensive? I believe it was pretty expensive the first time. Would that be covered by the dealership if they put a bad one in it? The car itself is outside of warranty.

Thanks!

Go to another mechanic. Exhaust has no suction, there is exit force coming from each cylinder and not possible for any metal from conferter to get Sucked in or even forced in. Furthermore the design of the exhaust manifold and heads would not allow entry of debries from exhaust to go up hill. If you are at a Nissan dealer then I doubt you are talking to a mechanic but you are likely talking to a service advisor. These guys are salesman and likely are full of sht. I very much doubt they are using synthetic oil unless you are specifically asking for it.

My test that i outlined doesnt lie. Pull dip stick out and wipe clean , if the metal on the stick is brown then it has had nothing but conventional oil.

How did the mechanic determine the the catalyst was about to go bad? Maybe they have an emissions tester. Sounds fishy to me though.

As far as the oil, it could be bad rings or possibly a leaking head gasket. Do you notice blue smoke coming from the exhaust? If so, that sound like bad rings. Is there any oil in the radiator fluid? If so then it would be a leaking head gasket but that much loss of oil doesn't sound like a bad head gasket.

Good luck though.

Thanks to all for the replies and suggestions. I absolutely trust my mechanic ... I've known him for 20 years and I know he's good. There's no way he would BS me in any way.

This stuff is over my head, so I'm going to print it out and bring it home for help.

Thanks again for the advice. Have a great day!

Very easy to do engine compression and leak down test. Leak down is the best test for rings.

I would not go to same mechanic no matter what you believe. He is full of it or you misunderstood what he said.

I know I'm bringing this back from the dead but I just registered and have been searching for a few issues I'm having.

First, I cured my slight oil burning problem by using Redline 5w-30 oil. It has a much higher HTHS than other 30 weights and higher than many 40wts. Much lower NOACK than just about everything else so less oil getting past the rings and less getting into the PCV system as vapor. It's an ester oil which these engines seem to like and not a dino base with an ester additive like Nissan sells. Seems to have quieted down the valvetrain significantly.

I had one question though, are catalytic convertor failures somewhat common on these vehicles? Mine has a few issues; pinging, a surge, and occasional rough idle which is pointing toward a bad or dirty MAF but I was on the lookout for convertor failures.

Just to contribute something to this old thread, oil burning will kill a convertor so the oil burning probably started the issue here. Exhaust is a series of pulses and it does not flow smoothly in one direction only. If the convertor is very close to the head like it is in my TL, and it starting to chunk apart, it's possible for the substrate to be sucked into the cylinder and score a cylinder wall. The chances are slim to none that it could ever get sucked into an exhaust port plus get past an exhaust valve which is opening 8 times per second at idle but it's a small possibility.

As crazy as it sounds, his mechanic is actually right. Some engines will leave the exhaust valve open slightly during the beginning stages of the intake stroke (just as another cylinder is on the exhaust stroke), causing exhaust gasses (and broken bits of pre-cat) to fly into a nearby cylinder; not to mention, these particles can also be carried through the EGR system. Nissan is actually known for this problem on specific engines, namely the 2.5L 4 cylinder used in the Altima, and the 2.0L engine used in the SE-R Sentras, and to a lesser extent, the 3.5L VQ35DE. This defect is well documented, and has been mostly corrected.

I have a 2004 murano with 191,000 miles driven that also burns oil. I frequently have to add oil as well. I have to say I've had no problems with my car except to replace the alternator as well as the oil burning problem. With the amt of miles I have driven after 8 years it only now needs its first fuel pump and suspension work. I couldn't have asked for a better vehicle

No blue smoke and no oil in radiator fluid for me but when oil gets low you can hear the sound of a chain and you better get oil in that car ASAP!

I have a 2004 Murano SL since 2009. Bought it with 50K miles and has almost 70K now. Several months ago in winter was driving and heard strange sound like someone was jack-hammering. Heard it again later while driving home then oil light flickered on. Checked oil on dipstick several times because was getting no oil on the marked side but was getting some oil on the back side. Turns out I was almost 2 qts low. Now I have to add oil frequently between oil changes which I only do about twice a year. Dipstick/oil level check is the worst I've ever experienced in getting an accurate reading. No oil burning smell, leaks, exhaust smoke, etc. Mysterious!

Just saw this thread and it is indeed possible for the honeycomb of a pre-cat or catalytic converter to break up and be sucked up into a motor. We've seen all kinds of things that have happened to members cars over the years and that is indeed something I would not have expected either.

There have been issues with the VQ motors and oil consumption. Some have installed catch cans between the PVC and where it returns to the intake manifold to monitor how much oil is going through the system. There is no fix for this other than a rebuild or motor replacement if consumption gets too high.

audtatious wrote: There is no fix for this other than a rebuild or motor replacement if consumption gets too high.

Long time no post and sorry for the zombie thread. But is this correct? Has no one figured out what the actual problem is and how to fix it?

I've got a 2005 Murano with ~140,000 miles burning about quart every 500 miles. So far searches all come up with 6 year old threads of a cat issue causing it but no fix.

Yes the cat honeycomb can get sucked into the engine on Nissan vehicles. Same thing with Hondas. The problem is that the cat is too close to the exhaust manifold. Ordinarily this wouldnt be a problem but if the engine is burning oil eventually the cat gets destroyed and then the cat materiel gets sucked into the engine. The real problem is that the engine was burning oil. Only 3 ways for that to happen 1) blowby gases -Getting a catchcan will solve that one 2) bad piston rings -major engine repairs to solve that one 3) oil leaking thru the valve guides- intermediate engine repairs to solve that one. Some 3rd generation Altimas 2002-2006 had bad piston rings which eventually killed the cat which then killed the engine. Other models too. Without engine repairs only other solution is to replace the cat regularly but that can be expensive. if you have no pollution laws get rid of the cats.


Alan

sharjt wrote:

audtatious wrote: There is no fix for this other than a rebuild or motor replacement if consumption gets too high.

Long time no post and sorry for the zombie thread. But is this correct? Has no one figured out what the actual problem is and how to fix it?

I've got a 2005 Murano with ~140,000 miles burning about quart every 500 miles. So far searches all come up with 6 year old threads of a cat issue causing it but no fix.

There's a few ways oil can wind up "missing."

1. Seal leak - usually fairly obvious if you're losing a quart every 500 miles.
2. Dirty/severely worn piston rings - The VQ series seems to have a bad issue with this. Nissan/Infiniti would run a test over time and replace the engine or, atleast, the shortblock, under warranty if it consumed too much oil.....but you're probably not under warranty anymore.
3. PCV Valve - this is a bit complicated.....
At the heat engines run at, some oil is kicked up as vapor and tiny droplets held in suspension. The PCV system continuously pulls air from the crankcase, where this oil is, and runs it through the induction system to be burned. Different oils behave differently at these high temps. If you never replaced your PCV valve, start there. If it's stuck open or closed, it can have bad effects on oil consumption. It's a cheap part and not too hard to change. This is where people often install "catch-cans" to catch the oil before getting to the induction system. I prefer to not do this because it's only a band-aid fix and can reduce the efficiency of the PCV system, not to mention introduce new places for a potential vacuum leak.

ok, im worning on a 2004 Murano, after a week of research, found that the oil burning issue is directly connected to the bad breathing system on the engine, pcv valve is hard to see so people tend to not replace it, vent baffle inside valve cover clog up easely and can only be cleaned by removing them, had one with a damage plug seal, so i replaced both, found a set on ebay for 75.00 cdn dollars, so this makes type of oil and replacement very important, plug seal are almost not replacebale so be carefull.