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Yes this has been covered in blistering detail on many websites, but for those new to this site/issue...

First, I don't pretend to be an expert, but I have rebuilt several engines and think I remember some of the basics. This will obviously be tainted with my own personal opinions. And being an engineer, I have also found some of the physics and chemistry behind this interesting. So, don't take just my opinion, you can find a lot of info on the internet about this topic.

There are many "camps" on this topic. I couldn't possibly cover them all but here are a few.

Camp 1. Smash it from the get go. This camp subscribes to the theory that if it is a good engine and you want maximum performance, you need to romp them from the start. After all, this is what racers do.

Camp 2. Drive it normally. This camp believes that you want to break in the engine the way you are going to drive it 90% of the time. After all, we aren't all racers.

Camp 3. Follow the manual. This camp believes the manufacturer knows best what the procedure is. After all, they designed the thing.

Camp 4. This is a myth. Todays engines and materials don't require breaking in. It used to be true, but the quality and precision of current manufacturing techniques makes this a non-issue. After all, this is the 21st century.



What is break in? The engine has to "break-in". Break in involves the process by which the moving metal parts wear into each other. While bearings and bushings wear together, the primary parts for consideration during break-in are the piston rings/cylinder bores. Camp one also believes its a good idea to weed out weak parts on day one.

The pistons have rings, both compression and oil. These rings and the cylinder bores must fit very closely together or the engine will not have proper compression and lubrication. Outside of the obvious benefit of lubrication, the rings also serve to scrape the oil off the bores on the down stroke so that oil is not burned during combustion. When the rings are not properly "seated" in the cylinder bores, full design compression is not achieved. When compression is not achieved, performance and gas mileage is adversely affected.

The internal combustion engine works by compressing an air/fuel mixture and igniting it. Basically a self contained explosion. The explosive force moves the piston which is connected to a crankshaft through piston rods. Thus the lateral movement of the piston is translated into rotational movement. If the compression is not correct, the explosion is weak.

A word about compression and octane. Higher octane fuels require higher compression. Higher octane fuels provide more power and burn better. With that said, a lower compression engine cannot make use of the extra energy in high octane fuels because they never achieve sufficient compression.

So one of the impacts of break in is obvious. You want the rings to seat to the cylinder walls. The rings and the cylinder walls are not perfectly round. They are very close, but not exactly. Therefore the cylinder walls are "cross-hatched". Which weeds out camp four because cylinders are still cross hatched. This cross-hatching is what allows the rings and the cylinder walls to wear together in shape very quickly. If the walls were perfectly smooth, it would take a very long time, if ever, for the rings and cylinder walls to wear together in a matched shape. In older engines where the rings are worn out, they will consume more fuel, burn oil and lose power. But these cross hatchings only serve their purpose for a short time. The "sharp edges" from the hatching wears off. The time it takes to wear off depends upon the materials of the rings, and cylinders. Also, maximum throttle and load can hamper the break in process. At maximum throttle and full load, the pressures inside the cylinder are at their highest and cause blow by. Among other things, blow by forces the rings into the piston and away from the cylinder walls. Exactly what we don't want for the break in process.

As the piston moves up and down the cylinder, the piston and cylinder vibrate. Very small amounts, but they do vibrate. And they vibrate differently at different rpms. That is to say the vibration profile changes with rpm. So if you run at a constant speed/rpm, the engine will take a "set" to a specific rpm/speed. This weeds out camp one unless you are a racer and want an engine that only works best at highest rpm. This also weeds out camp two because we do occasionally want high rpm performance, depends on definition of "normal" driving. For the rest of us,what we want is an engine that will achieve compression at all rpms.

Lets combine all this and say that during break-in (the first few thousand miles) you do not want to drive at a constant speed/rpm. You do not want to go to full throttle/load. What you want is to constantly vary your rpm's throughout the throttle/load range but staying away from max throttle/load at first ending up at primarily max throttle/load towards the end of break in.

To stay within the manual recommendations, first 1200 miles keep rpms under 4000-4500 and maybe a few excursions into full throttle. After that, gradually increase rpm range to 6000 with several excursions into full throttle. Find a road late at night with few people cause the constant accelerating/decelerating will drive people nuts. And obviously, you can't do this up/down yo-yo thing all the time, but do it. It works. Avoid driving for long periods without doing it. What is long periods? Tough to say but I try to avoid 5 minutes or so of constant speed driving at first then gradually lengthening the time to 15 minutes. Use the Ds and L modes to help with this. If you want to venture out of camp three, accelerate the mileage IE instead of 1200 miles, use 500 instead.

A note about the VQ35DE and it's computer control. The VQ used in the MO and the 350Z has a computer that "learns" the way you drive. (It is akin to a kalman filter by my way of thinking for those engineers out there.) As it breaks in and you drive differently, the computer will adapt and change how much power it provides you by way of changing how much fuel it provides. It senses the engine rpms and the throttle positions with respect to time. Given the VQ has VVT, it probably also changes that.

The affect you are looking for is that the car should get "stronger". I don't know how else to put it. But as the engine breaks in and you increase your excursions into full throttle/load, as a result of the rings seating/break in and the ECU, the engine creates more power and it just feels stronger (butt-dyno).

It has been proposed (not confirmed) that the computer also kicks in more aggressively based on ODO miles.

Some of my experiences...

First let me say that I broke in my 350Z and my MO with this process and I am very pleased with the results.

Secondly, this process was taught to me by my father who rebuilt more engines than I will ever know and was into racing at one time (until mother threatened to divorce him). Some of the engines I have rebuilt for myself/friends worth mentioning include the 280Z, 390 Ford, 383 Magnum - Dodge Superbee, 460 Ford. The 280 was amazing. With over a 100,000 miles you could still see the hatch marks in the bores. The dealer service rep I talked to at the time claimed the bores on the datsuns were nitrided (never confirmed). The 390 Ford was straight forward, 80,000 miles but I had to hone the bores, re-hatch, and get oversized pistons. The 383 I learned about chrome rings and Rislone. The 460 had only 1200 miles on it. My friend replaced the stock cast iron intake manifold with an aluminum edlebrock when he bought it, but forgot to clean it out first. Must have had sand in it because the engine lost compression big time. When we took the engine apart, you could see a worn lip in the cylinders and wear on the pistons. Only 1200 miles! Needless to say it's now closer to a 490 and after many years and miles of reliable service my friend can still melt the tires.

All the engines I rebuilt were broken in using my fathers tried and true method. Followed each up with wet and dry compression tests to make sure the rings and valves seated. All I can say is, it works.
 

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Enforcer,
Wow what a great post. Just one more question – which oil to use during breaking in: synthetic or petroleum based?

ECU learning - I had, in middle 90’s a Mitsubishi Magna, an Australian made car equipped with an adaptable automatic transmission with grade logic control. One of the features was that the car “learned” the drivers behavior. So, should you start driving “sporty” after a few miles car would start shifting transmission using more “sporty” algorithm. If you drove “economically” car would learn this as well. It was amazing to get into the car after my wife drove it. I would recognize it immediately. And of course vice versa.

Another nice feature was grade logic control. You would drive up hill and car immediately would select right gear. There was no hunting etc. Driving downhill – car would lock to the right gear to make car brake. I remember driving downhill on a long twisty road. I used brakes only a couple of time while the car at front of me cooked the brakes. In the end I head to back off because of nasty smell!

Anyway, really nice job, Enforcer. Just keep posting!

;)
 

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Discussion Starter #3
Thanks, well...sometimes my memory ain't so good. Got into this stuff 15 years ago.

Anyhow, I believe mineral based is what should be used for break in. Synthetic would extend the effect due to its higher lubrication ability. I also believe in changing frequently during break in.


(Edit)

I should also say that the the Z (and probably MO) shipped with a special break in oil. I could tell on the Z because at first oil change the pressure changed dramatically. There is a camp that says you should absolutely not replace this oil until recommended. And this camp also believes that the idea of particles in a new engine needing quick replacement is a myth with todays quality. - Maybe, but I know what I do works.
 

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Break in

It would seem then that going long distance to get an MO from a dealer several states away and then driving the MO back home would not be a good thing to do if you wanted to break the car in properly.
 

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Breaking in

Enforcer, excellent article.

I was not aware of the intricate details for the breaking in process that you have mentioned. Speaking of which looks like I didn't break in my MO properly. Currently its at 2700 miles. I always drove at constant RPM - under the impression that it would be proper way to break it. Also my mileage seems to be decling over past few gas fills. It was giving 18 miles on city roads and now gives around 15 miles. Could it because of the breaking in process not followed correctly ?

Any suggestions as to what to do next ? Also is it possible to reset the computer's learning curve to a new proper value or it automatically adjusts over time to new driving habits.

pkhona
 

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Discussion Starter #6
I wouldn't say it's not broken in properly yet, more on that later. But it's not the cause of the lower mpg. The idea of varying the rpm is so the engine doesn't take a set at a specific rpm. If your driving the same roads at the same speeds then it would break in to that, thus not the cause of the lower mpg. Probably as you get used to driving the vehicle and get more comfortable with how you and it interacts, your just getting lead footed meaning your varying the rpm more than you realize. Could also be gas, even if you buy at the same place. There are winter and summer blends and then switches in suppliers etc.

Keep in mind, that if you broke it in how you normally drive, then it's not all bad. It may have taken a set at lower rpms but if that is how you normally drive then so be it. If you want an all around performer, then start the break-in procedure now and be more aggressive about it up until about 4000 miles. Your mileage is going to stink, don't worry about it, but it has a chance of still working. Focus on the above 2500 rpm ranges (I just drove in S and L a lot) at first with about 80% throttle. After about 200 miles of that, go full throttle, work that 2500-redline range aggressively.

Yes, you can "reset" the fuel maps in the ECU. Disconnect the negative terminal on the battery and leave it disconnected for 15 minutes. It will relearn fairly quickly though so I wouldn't worry about it. And you can't change the ECU cut-in effects based on mileage...if they exist (I think they do but can't prove it).
 

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Hi,

Thanks a lot for this info. I shall try the breaking - in procedure now as you have suggested and see how the car responds then.

Most likely I will not reset the ECM yet and do that after the breaking process , hopefully at that time I would start driving normally.

Regards,

pkhona
 

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I just received my MO last week, so I just started the break-in process. I really liked Enforcer's technical explanation of the break-in process and completely agree with his analysis of the various phases of the break-in, but I wanted to post another break-in procedure similar to Enforcer's, however, with more emphasis on the early stages of break-in. Based on my research, most of the engine break-in occurs in the first 500 miles, and therefore, this is the best time to vary the rpm's.

Here is the procedure I am using:
1. Drive conservatively the first 100 mi keeping the rpm's under 2500. Vary speed. No cruise control. Don't drive over 60 mph.
2. Change the oil (mineral based), oil filter, and crush washer.
3. The rpm workouts: each workout starts with a complete engine warm-up (driving normally). Then, using the rpm ranges stated below, start at the low end of the rpm range, accelerate to the high end of the rpm range (not a hard acceleration, just a constant acceleration), and coast back down to the low end, repeating this process for 10 minutes. After the workout, allow the car to completely cool down (usually about two hours) before performing the next rpm range. Here are the rpm ranges:
2000-3000
2500-3500
3000-4000
etc...
5500-6500 (the last rpm range staying under the redline)

You will need to use the Ds gear (in the lower rpm ranges) and L gear (in the higher rpm ranges). Make sure you find the correct roads for these workouts. A four lane road is good, since you don't want people to be stuck behind you when you do this. Also, several roads with different speed limits will probably be needed.

4. After the workouts, change the oil (mineral based), oil filter, and crush washer.
5. Drive conservatively until 1000-1200 mi. Vary speed. No cruise control.
6. Change the oil (mineral or synthetic), oil filter, and crush washer at 1500 mi. I choose mineral until 5000 mi, but sythetic should be fine after 1500 mi.

I know people who have abided by this break-in process with excellent results. Hope this helps!
 

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Very in depth article, good show. :)

My dealer gave me minimal instructions for break-in, concurrent with the owner's manual. I'd say following those instructions are your best bet. Besides those, you could dig deeper and follow Enforcer's suggestions, such as interspacing normal highway/city driving with some high-end blasts of speed on straight, clear roads.

I remember a mention in the service manual that you can reset the MO's learning computer with a certain sequence. I think it was four or five turns of the ignition to the position before "start" .. ya know, when the engine starts. I'll have to check again on this one. I guess it could come in handy, but if the learning CPU is constantly learning (and therefore doesn't lock into one specific behavior) I imagine any time when you confused it, it would work itself out eventually after more driving/learning.
 

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Doombringer said:
Very in depth article, good show. :)

My dealer gave me minimal instructions for break-in, concurrent with the owner's manual. I'd say following those instructions are your best bet. Besides those, you could dig deeper and follow Enforcer's suggestions, such as interspacing normal highway/city driving with some high-end blasts of speed on straight, clear roads.

I remember a mention in the service manual that you can reset the MO's learning computer with a certain sequence. I think it was four or five turns of the ignition to the position before "start" .. ya know, when the engine starts. I'll have to check again on this one. I guess it could come in handy, but if the learning CPU is constantly learning (and therefore doesn't lock into one specific behavior) I imagine any time when you confused it, it would work itself out eventually after more driving/learning.
Hmm what page of the FSM shows this procedure? I think this would be very helpful if this allows you to reset the computer without having to use a scan tool or disconnect the battery cable, in case check engine light codes come up.

One thing I hate about the Murano is that there is no way to check the CEL codes unless you have a scan tool. In my 97 Maxima, all you needed was a screwdriver to check the codes. Might not be important for the normal driver, but if you want to modify your Murano (such as intake mods) it might trigger check engine lights.
 

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Since I am a double ASE Master Certified Mechanic (was, gave it up when I slipped a disk in my back from being a heavy equip mech. as well) Heavy Equip Master Mechanic, and Automotive Master Mechanic. I am very proud of those cause I was 22 when I finished both of them and was one in 5000 mechanics in the US in 94 when I finished them.

So I will give my 3 cents. Enforcer has a good plan.

The bottom line is to drive relatively conservative for the first 1500 miles or so, using different speeds along the way. Never driving a constant speed for longer than 5 min or so.

Then start to drive a little more aggresively, full throttle take offs, passing people, getting rpm's up there for a short period of time.
Then continue to drive this way and enforcers way until the 3500 mile mark. Then do an oil change.
After that you can pretty much drive whatever way you choice.
Do not do an oil change prior to 3500 miles. As the oil needs to "Set" as well. It changes with the heat and everything else in an engine and sets up with it. This is my personal opinion, not a proven fact.
I also wouldn't use synthetic oil until after 3500 miles, which to me is the end of the break in period.
I would also recommend getting a K&N air filter to allow for more air intake into the engine. This helps in numerous ways, to include keeping the valve train cleaner by having better combustion with more air. It will also pay for itself by the savings in gas over the long run.

As far as changing oil with synthetic and timing. I would change the oil at the recommened levels as far as your manual goes regardless of what the oil says. Unless you want to have to deal with the dealer when something happens to your enginen and they blame it on you waiting to change your oil every 5000 miles, when they said to do it every 3750. I would also change the filter ever time as well. Some people don't believe it or not. I use Mobil 1 due to my knowledge of what I have seen inside torn apart engines with the other different oils out there. Mobil 1 just seems to be the best, and longest tested in my opinion.
I would also recommend changing the transmission fluid in this vehicle exactly as prescribed due to the CVT.
I would also have a brake system flush and refill either every 2 years or whatever the manufacturer recommends. Brake fluid by its make up, attracts water. Which is not good for your abs system. It also gets dirty. Which will harm the pistons in your ABS unit and other brake parts. ABS units are outrageously expensive. So the cost of doing brake fluid flushes will pay for itself if you never have to replace an ABS unit.

Also, tire pressure is a BIG thing. I would check it at least once a month. It affects tire wear as well as other things like gas mileage. And more than you would think. I would also invest in a digital tire pressure gauge to get an accurate reading. Using the ones provided on the tire pressure filler is a questimation at best.
Rotating tires either every oil change or every other oil change, front to back, due to most new tires being steel belted. This will save in the longevity of the tires very much. ALWAYS make sure they use a TORQUE wrench to reinstall your lug nuts so your rotors do not get bent by having uneven tension no the lug nuts.

As far as fuel, I would run 89 or above due to the high compression of this particular engine. It will save you in the long run. Even running 91 would be best. Also adding fuel injector cleaner every couple of fill ups will help keep things clean inside the cylinders, as well as the injectors. NEVER buy it from the gas station. Pick it up at Wal-mart and always keep a few on hand in the trunk hidden carrier.

I also am a very big advocate of using RainX. It works wonders on your windows. It is like waxing your windows, I guess would be the best way to describe it. With my Porsche, I never had to use the wipers, cause the Rainx would keep the rain beaded and blow right off the window. I also use RainX wipers, and RainX wiper fluid to always keep the windows clean and ready to bead up and blow off all the rain.

Lastly, if you live in a state or area where you get snow, I would keep a tow strap, a good one, they have em' at Wal-Mart, they are yellow with hooks on both ends. I would buy the 30ft. This will ensure you can help someone who is stuck and pull them out. The longer distance of the tow strap will ensure you can be far enough away to be on a decent surface to pull them out, and you can always make it shorter by double looping it.
I would also keep any other type of survival, ect. gear in your truck in case something happens and you are in the middle of nowhere. Oh ALMOST FORGOT, Wal-Mart also has this fuel transfer pump thing, where you put one end in your tank and tthe longer end in your favorite new buddies tank. It has a bulb on ita, and all you do is pump the bulb and it will transfer fuel for you, if you run out. It saves a lot of time and trouble if your run out of gas, or on the other hand if someone else runs out of gas. No taking them to the gas station, buying a fuel tank, filling it up, driving them back, ect. Just plug it into both your tanks, pump the bulb and they will have enough fuel to get to a station to get more. And they only cost $1.99 for these things. They are a life saver for you, or someone else if you are out of fuel.


These are just my feelings and opinions from the knowledge I gained while being a mechanic. Some may be right on, some may need a little adjusting, and some may thing some things are off. Any corrections or conflicting ideas are welcome and are really what a message board is for.

Preventative maintanance is the key to keeping your SUV running good and keeping the costs low when it comes time for repairs.


I hope some of these ideas help at least one person out there, then they were worth typing.

These are just things I have learned over the years that I felt are worth sharing.

Chez
 
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