Where does the engine oil leak from?

[BlueHorse]

2004 Murano SE AWD, 90K miles.

It consumed ~3 quarts of engine oil in last 6,500 miles. My mechanic says must be piston ring is bad. But after an oil change at the shop, I noticed today that there is oil above the lower oil pan, and I verified there is no leak from the oil drain plug. From the location of the leaked oil, it is in my opinion not likely to come from either the oil filter or the drain plug.

Take a look at the picture. The leak area starts from the upper edge of the lower oil pan (marked as #1 in the picture), and stops (mostly as far as I can see) at an edge a little higher above made of aluminum (marked as #2 in the picture). There is much less oil if any higher than this point (marked as #3). Note location #2 is between the oil pan and the center of the vehicle (Cat converter goes through there, but it is to the left outside the picture).

Any thought where the oil is leaking from? And how difficult to fix? Average cost if goes to an independent shop?

Thanks!

[nitely]

Maybe from the oil cooler creeping down to that point? Do you have a wider angle shot? Or the oil pan seal is bad?--not common.

[turbizzy]

To be honest and without really seeing it for myself, here's what I can tell:

1. From that pic, the "leak" doesn't seem that bad. It could be the engine oil cooler gasket starting to leak but it doesn't look like very much oil is leaking yet.

2. 3 quarts is 6,500 miles is not too shabby! But its not great either. I see alot of VQ35DE engines consuming about this much oil on a daily basis and this is why I stress more frequent oil changes such as the dealer recommended 3,750 miles, not nissan's 7,500 mile recommendation. What if you are burning oil, then what? At your rate, you would run out or very low on oil by the time you reach 7,500 miles!

3. Yes VQ35DE engines are notorious for oil control rings going bad especially if oil changes are not kept up. I don't know why nor do I know why the VQ30DE engines of the 95-01 Maximas were so bullit proof even with low oil levels but thats just the reality. I've replaced dozens and dozens of VQ35DE's in all models of Nissan for excessive oil consumption. Can't really put my finger on the reasoning other than most of the time the owner can't provide accurate maintenance records or too long between oil changes, etc. Also premature catalytic converter failures can cause catalyst material to break apart and be sucked back into the engine's exhaust ports damaging the piston rings but in my opinion, oil consumption damages the cats and I think thats what ruins then which then ruin the engine even more and the cats get the blame.

If it makes you feel any better, my 2004 Murano with 129k miles does burn some extra little oil i've noticed. But I do my oil changes at 3,750 miles and from what i've found, im burning about half a quart every 1,200-1,500 miles but it never really sees highway miles, mostly in town and thats the worst driving, short trips, engine not reaching operating temps, etc. But I have started using Mobil 1 fully synthetic 5W30 and have noticed it burns less oil now, maybe about half a quart in about 2,000 miles. Mobil 1 and synthetics in general claim to have better oil additives that protect against oil consumption, worn rings, etc so why not try that?

[BlueHorse]

Thanks guys. Is oil cooler the shinning metal casing where the oil filter is attached to? If you guys have a picture of where oil cooler is, that will help.

I never noticed drops of oil on my garage floor, so leak (if any) is indeed small. What I am HOPING to confirm is that the oil loss I experienced is due to leaking to external environment, as opposed to engine piston ring problem (later is much more expensive to fix I think).

What is the aluminum block at location #2? Is it the upper oil pan, or transmission block? I am thinking maybe this is where it is leaking because it is the highest point with oil. Will oil cooler leak get to this location?

Lastly, an administrative question - I am planning to use a brush on a long stick to thoroughly clean out the leaked oil, and drive for another 500 miles and check where the leak is. This will rule out the oil change guys spill the oil around 2 days ago (I doubt though). Will clean up mess up signs of evidence?

Thanks!

[BlueHorse]

Originally Posted by turbizzy

2. ...What if you are burning oil, then what? At your rate, you would run out or very low on oil by the time you reach 7,500 miles!

3. ...Can't really put my finger on the reasoning other than most of the time the owner can't provide accurate maintenance records or too long between oil changes, etc. ...

If it makes you feel any better, my 2004 Murano with 129k miles does burn some extra little oil i've noticed. But I do my oil changes at 3,750 miles and from what i've found, im burning about half a quart every 1,200-1,500 miles ...

The ~3 quarts lost oil in 6,500 miles did create a big problem for me – according to my mechanic, low oil pressure messed up timing, and led to Service Engine Soon light on. During the 2 days the SES light was on, I also heard small metal parts making noises during acceleration within only the first 3 min. after cold start in the morning. The noises went away after new oil change.

Bad maintenance can’t explain my case. I had Nissan Gold Service Contract since bought new till ~75K miles (including synthetic oil change per 3,750 miles). After that, I did oil change with Mobil One every 4,000 miles except this last change I stretched it to 6,500 miles.

Do you use conventional oil at every 3,750 miles? I plan to keep using Mobil One, but wander if I should use 5,000 miles schedule instead of 3,750.

[Pilgrim]

Originally Posted by BlueHorse

The ~3 quarts lost oil in 6,500 miles did create a big problem for me – according to my mechanic, low oil pressure messed up timing, and led to Service Engine Soon light on. During the 2 days the SES light was on, I also heard small metal parts making noises during acceleration within only the first 3 min. after cold start in the morning. The noises went away after new oil change.

There are some danger signs in what you wrote.

1) You didn't check your oil in 6500 miles? That's how I interpret your first sentence. This is never a good idea.

Bad maintenance can’t explain my case. I had Nissan Gold Service Contract since bought new till ~75K miles (including synthetic oil change per 3,750 miles). After that, I did oil change with Mobil One every 4,000 miles except this last change I stretched it to 6,500 miles.

...and now you know that you made a big mistake. All it takes is once. My comment is that this IS due to poor maintenance - yours. You neglected to get the oil changed and didn't even check the oil level. There's nowhere else to point the finger. Nothing personal, but since you screwed it up, 'fess up.

2) The SEL light staying on for two days is worth checking. I can't say I blame you for not going into panic mode and dropping everything to have it checked - I would not have either. But I would have made an appointment for a shop to check it.

3) When you hear odd noises from the engine, I think you would now agree that checking the oil level is a very, very good idea.

[Mr3Putt]

Oil consumption was one of my biggest peeves about my Murano.

It was ridiculous how much oil that car consumed.

Just because most of them do, still doesn't make it acceptable.

[zebelkhan]

Another common place for the oil to leak on VQ is the valve cover gasket on left side of engine (close to firewall). Most technicians replace that gasket when replacing spark plugs.

[BlueHorse]

Originally Posted by Pilgrim

There are some danger signs in what you wrote.

1) You didn't check your oil in 6500 miles? That's how I interpret your first sentence. This is never a good idea.



...and now you know that you made a big mistake. All it takes is once. My comment is that this IS due to poor maintenance - yours. You neglected to get the oil changed and didn't even check the oil level. There's nowhere else to point the finger. Nothing personal, but since you screwed it up, 'fess up.

2) The SEL light staying on for two days is worth checking. I can't say I blame you for not going into panic mode and dropping everything to have it checked - I would not have either. But I would have made an appointment for a shop to check it.

3) When you hear odd noises from the engine, I think you would now agree that checking the oil level is a very, very good idea.

I agree it is my fault. At point of writing my first post, I was thinking long interval oil change is the problem, but now I know the problem is not checking oil level every 1K miles.

[BlueHorse]

Originally Posted by zebelkhan

Another common place for the oil to leak on VQ is the valve cover gasket on left side of engine (close to firewall). Most technicians replace that gasket when replacing spark plugs.

Left side of engine is the side facing passenger side, or driver side? I see oil leaking facing backside of the car, between the oil filter and the center line of the car.

[nitely]

Its bank 1 facing the firewall. Bank 2 facing you when opening the hood. 3 plugs each bank.

There is a diy on replacing the oil cooler gasket. Very easy if you are handy. Thats if you are sure thats where the leak is coming from.

[BlueHorse]

Originally Posted by BlueHorse

What is the aluminum block at location #2? Is it the upper oil pan, or transmission block? I am thinking maybe this is where it is leaking because it is the highest point with oil. Will oil cooler leak get to this location?

Any answers to this question here?

[nitely]

The best way to see where the leak is coming from is to clean up the area then observe it every day. Do you have some tools in your garage?--like floor jack, jack stand. Its hard to tell until you start clean. Shops will do the same.

[zebelkhan]

Originally Posted by BlueHorse

Left side of engine is the side facing passenger side, or driver side? I see oil leaking facing backside of the car, between the oil filter and the center line of the car.

Murano engine is mounted sideways so it's left side is towards the firewall (aka bank 1) and its right side is towards the radiator (aka bank 2).

[BlueHorse]

I visually checked the oil cooler today and saw no sign of new oil leak there. Will check again in a week to make sure.

Then I took the engine cover off, and interestingly saw 3 places that appear to have oil seepage (marked #A, #B, #C in first photo attached). #A appears to have caused the leak I saw near oil pan below.

2nd photo shows where oil seepage is seen in location #A. And 3rd photo is a close up of same location, showing that green connector covered with oil. What is this connector? Unsure if oil is seeping from the connector or elsewhere.

4th photo shows seepage at location #B, which I think is near the gasket of bank 2 valve cover? Just tiny bit "moisture", no build up of greasy oil.

5th photo shows some oil build up close to the engine oil cap. It maybe leaking from that hose I marked (what is it?), or some spill over when filling fresh oil. I will clean this clean this location #C, and wait some time to confirm either way.

So, what do you guys think are causing the leaks, esp. in location #A and #B?

Should I clean up leaks related to #A and #B, and wait some time to check again? Or the evidence should be clear by now for the dealer to decide on fix (I don't plan to do all these fixes myself). The fear to clean things up now is that I may make a mess and complicate dealer's assessment.

Thanks guys!