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What are your thoughts on engine break-in? Some say follow method, which is drive it like you stole it the first 20 miles. Others say vary the rpm's the first 600 miles and some just follow the manual which says take it easy the first few hundred miles. I've posted a thread on another forum and the consensus their was that it doesn't matter. Some have broken in their cars easy and have had no problems, other hard and the same thing. I think it's safe to say that cars today don't need sophisticated break-ins due to modern technology. Thoughts?
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One of the big factors in the break-in is the hone job done by the manufacturer/cylinder shop. This is out of your control.The key to this process is to do it reasonably quickly and with moderately high power. If it's done too quickly the cylinder walls will gall and ruin the rings; too slowly and the rings will anneal and glaze the cylinder walls.

The secret to break-in is allowing the rings to wear on the cylinder walls without getting them too hot.

The rings are made of tempered steel that's affected by temperature. The higher the temperature of the ring, the less time required to anneal or remove the "spring" from the metal.

When the ring anneals, it loses its ability to exert pressure against the cylinder wall. This inhibits the transfer of heat to the cylinder, causing the ring to retain heat and anneal further, thereby aggravating the situation.

So it would seem that a good thing to do is to keep the piston and rings cool and keep pressure on the cylinders and run at approx 70 percent power

Turbocharged engines run much hotter than naturally aspirated engines, especially as the pistons and rings are concerned.

With the constant and usually higher pressure on the rings in a turbocharged engine, the rings will have enough contact with the cylinder walls to break in quickly.

With cam and lifter contact is inevitable because of the extreme pressures put on the lobe and lifter. Each lifter and lobe wears into the corresponding surface in a particular pattern. Until broken in corrosion may be a problem so frequent use helps to break-in quickly.
Breaking in for car engines is now "obselete." The engine metallurgy has changed over the years and more and more Aluminium and alluminium alloys are being used today. The manufacturing and machining process have also become high tech. Today the cylinders are super honed and most Auto manufacturers do not suggest "breaking in" at all.

Hussam Adeni
Break-in is not only for the engine, it's for more than that. From experience, the Owner's Manual of ours states that it's important not to use excessive breaking during the first 800 kms approx. Re - engine, most enigne oils will protect better now than they did ten or twenty years ago so this may have some impact on reducing the necessity for the traditional break-in. A shorter oil change interval during the first three, four or five thousand kms is always a good thing no matter what. New filters would be obvious.
Most of those things you do for a break-in can't hurt anything and may help if there is something a 'little off'. So if it's your car, it's like a bit of insurance.

This could lead to talk about that first oil change. Some of the additives found in factory fill oil, represent fall-out from assembly more than a special oil. If the engine is assembled and there is some lag time till it gets installed and some more lag time until the car/truck gets shipped, stored in a lot, driven in short bursts until it's sold, you have a car that should have it's first oil change very soon after being delivered, based on time. All this has got to be considered in the break-in of new car.

I do some maintenance software that tracks and manages all kinds of stuff. There are some new vehicles purchased in the past few years that have over 500 days from build until purchase. These vehicles were Fords on long rebate deals and others were over 300 days. They received their first oil change real soon after being put in service.
I have a Dodge Ram diesel that supposedly, wasn't to see a synthetic based oil for at least 6000 miles....well, I left the junk they call oil from the factory in for 1500 miles or so, and have never looked back onto petroleum based product again.

She just turned 100K miles and is motoring along just like when she came off of the showroom floor, maybe just a little bit more wear and tear, though... Wink
After 30 years of building engines (cars, motorcycles, and even aviation related engines) it's my opinion that the "run it hard" method provides the best break-in and longevity for an engine. Understand, this does not mean just run the heck out of it. There is a proper procedure for doing it.

In fact, in the aviation world, this is the method used. I don't know too many people that will argue that engine reliability and performance are not paramount factors in aviation, for obvious reasons.

If you doubt this, then you can check for yourself by reading this article on Cessna Aircraft's site:

The science behind this method is sound and proven.

Keep in mind that a proper break-in is not just about seating the rings for performance. The prevention of blow-by is important as contaminants quickly degrade engine oil, seriously reducing engine life.

The use of synthetics for break-in is indeed a bad idea. The lubricity of synthetics does not allow the initial desired friction and wear to occur as well as petroleum based oils do, thus extending the break-in period and garnering the associated issues with it.

Glazing of the cylinder walls is a common problem when engines are broken in according to the owner's manual (i.e. "babied"). I've seen it too many times first hand.

Modern metallurgy and machining accuracy has indeed changed the break-in procedures, but these changes have only manifested themselves primarily in terms of the time it takes and the level of precision the break-in can achieve. The basic science of why it is done has not changed.

Modern technological advances in cylinders (nikasil, ceramic linings, etc) have allowed engine break-ins to occur in very short periods of time (some in as little as 1 hour). The reason is how these linings retain oil on the cylinder wall, how fine their finish is, etc (porous vs peak and valley scratches of honed steel). However, the science and mechanics of why and how to brak-in are no different.

The more perfect the seal of ring to cylinder, the better the engine performs and the longer it lasts. The only way to achieve this kind of fit between two metal objects is to rub them together and allow them to wear into each other. Due to heat and contaminants and their effects on oil, the faster you can conclude this break-in, the better.
Almost all new vehicles have the engines broken in long before the customer get them. They are driven off the assembly line, on/off the trains or car haulers, around the dealer lots and often customer test drive. I have never seen a new car with less that 5 miles on it and I bet the run time approaches an hour or more. Around here in the winter its not unusual for the dealer to be moving cars around all winter to make room for snow removal, lots of idling time.

btw-If synthetic oil was not good for new engines, why are some many MFG's installing it in new cars?

Many people are living in a time warp and refuse to beleive modern technolgy.

Last year I had to install a new 5.0L engine (cracked block from overheating) in my 92 Chevy plow truck. The GM dealer called me up and said, we can't put that synthetic oil you wanted in the new engine, do you want it use something else? Say what, I said. You sell new Corvettes with synthetic oil but I can't use it in my new GM engine? Don't you dare install another oil or I will be a mad customer. They put in but were against it. Over 1 yr later, many hours of plowing snow and the engine is running fine. To hear the GM tech talk, I would not make it home. LOL. I could not beleive an Corvette dealer would be so down on synthetic oil, I hope none of their Corvette owners got that critism for wanting synthetic oil installed when it mandatory on the Corvette because only synthetic oil meets the required oil spec.

Mobil 1 is factory fill in:

* Aston Martin
* Bentley Amage and Bentley GT
* Cadillac CTS, XLR, SRX and STS
* Chevrolet Corvette
* Dodge Viper
* Mercedes-Benz AMG vehicles
* Mercedes SLR
* Mitsubishi EVO
* Pontiac GTO
* All Porsche vehicles
Last edited by miker
Here are the comments from a GM engineer I was lucky enough to speak with. Nice guy and had some great things to say about this topic.

Some oil consumption is of absolutely no concern to me, personally. Niether is it a concern to the engineers that design and develop them. Mostly it is just an inconvenience (having to add oil occasionally). Only car owners seem to be upset by oil consumption.

I think most people's analysis of "why engines burn oil" is based on the (false) idea that an engine shouldn't burn ANY oil and if it does burn some oil then something "must" be wrong and they invent all sorts of logic to explain why it happened. Most all of it is nonsense.

Occasionaly use of full throttle and high RPM is the easy, simple and fun way to eliminate deposits and keep the combustion chambers clean.

Most high output engines will always use some amount of oil as keeping the top rings lubricated at high loads and high RPM is impossible without loosing some oil past the rings. Plus, multivalve engines need to keep all those valve guides/stems lubricated and that is only accomplished with "total loss" oiling.

I doubt seriously that breakin or anything else would have affected the oil consumption. Provide a dose of high RPM WOT accelerations as often as practical to keep the chambers clean and the rings moving and free on the pistons.

Many engines have very aggressive cylinder wall finishes to maintain oil on the cylinder walls to keep the rings lubricated at high specific power levels. This often leads to high oil consumption and variable oil consumption from engine to engine. None of them are "good" or "bad" ..... just some of them use more oil than others.

If the engine is not smoking I would say that the oil consumption (no matter how high it is) is fine and that nothing is wrong. If the engine suddenly starts to smoke and use oil then something obviously changed or failed but low levels of oil consumption are perfectly accecptable.

BMW had such high oil consumption on some of their M engines that they caution to check the oil at EVERY fillup on the autobahn type driving as the engine can run low on oil in a slightly longer interval. They actually replaced engines that failed from oil starvation due to the high rate of oil consumption that was "normal" due to the aggresive cylinder wall finish and low tension ring pack.

The fits and finishes in most production engines these days means "breakin" is pretty much a non issue. I have seen many engines torn down that were broken in in different ways from full throttle operation instantly to gentle driving to no particular breakin at all. They all look fine.

The one thing you usually want to avoid immediately with a new, high performanc engine is revving it to the redline and holding it there. The oil filter will almost always be bypassing to some extent at the oil flow at high RPM and any debris generated during breakin will bypass the filter and end up in the bearings. If the cylinder walls are a cast iron material (either a cast iron block or inserted aluminum block) this means that the cast iron scraped off the cylinder walls during the first few minutes of operation needs to be trapped by the oil filter. Cast iron in the bearings is not good. The high RPM would not hurt the cylinder walls at all but the debris needs to be caught by the filter. That is why all the filter arguements on the internet are so
The factory may dyno run these new engines on mineral, then factory fill.

No so with Corvette production. And, besides, if it added two cents to the cost, changing oil, no factory would do it.

We have a racing program and put synthetic oil in for assembly and first run on the dyno. I read the aircraft break in procedure and the only part that I would not follow is holding the engine at idle speed on first startup. We start engines and take them to 2,500 rpm and hold them there for about 15 to 30 minutes while looking for problems. We feel that engines oil better with a little more crank speed. After that we shut down, check everything, let the engine heat cycle to cold and start the power runs on the dyno to get the engine tuned up and ready for some track time.

We've done leak down tests on new cars and pickups, and have never found one that did not pass, brand new. You don't perform well on a leak down if the rings are not completely seated.
Heat cycling is another myth in the engine industry. The premise behind heat cycling is such that it is supposed to releive any stresses built up on the metal components as a result of forging and or milling, forming, etc.

The problem with "heat cycling" is that the temperatures required to stress relieve metals is far, far higher than the temperatures reached by a running engine.
The lubricity of synthetic oils is higher than petroleum. There is quite a difference between the two.

Natural oils are composed of hydrocarbon molecules that are of various sizes. Synthetic oils contain single size molecules, small ones. This accounts for it being "slicker" than petroleum oil.

Sythetics are made from esters, or in some cases, specially refined petroleum products, just depends on the method used.

As mentioned before, modern metallurgy and manufacturing processes have changed the methodology of break-in, but not the reason why.

The goal is not to wear the roughness of a new cylinder completely down, you need voids or pores to hold oil on the cylinder wall, or there won't be any lubrication happening.

As to why car manufacturers send out new vehicles with synthetic oil is a good question. It's not a good practice. Then again, all of them also recommend that you baby the engine for break-in. Probably any number of conspiracy theories there.

Think of it this way as well, we've had the technology for years to use alternative fuels and/or to get much better mileage than we get now, so why isn't it made and sold?

It's all about money.

Letting oil blow by the rings is not how you want to lube your upper rings. Oil is retained in the fine scratches of honed cylinders and in the pores of exoctic cylinder linings. That's how the rings get lubed (or at least, should get lubed).

It is impossible to completely seal the rings to the cylinder. No matter how well the break-in is achieved, some blow by will occur. A good break-in will minimize it, but not completely eliminate it.
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