The Mileage Theory

The 40 km/h limitation is ridiculous. Keeping below 80 km/h might make some sense, but I'm not sure that even this is necessary. Let the engine warm up well before driving, and accelerate moderately; this should be sufficient for "breaking in."

It's whatever the manufacture states. I have no idea what vehicle the original poster was citing as an example, so, when in doubt, consult the owner's manual.

Thanks folks,

So it has nothing to do with increasing mileage, but it is just set the vehicle, the seals, bearings, drive train.

*40Kmh- 40 Km/h

http://www.google.co.uk/search?q=bedding+or+running+in+of+engines&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GGLT_en&redir_esc=&ei=2pHNTIC1CcKSjAfjwZXWBw

bearings break in after the first minute,it is the rings that take a bit of time to break in. The harder the ring material the longer the break in.Chrome moly rings take forever to break in.It is not un common for an engine to use a quart of oil in the first 3000 miles. I am a big fan of using a magnetic grain plug,you would be surprised at how much very fine metal sticks to it.On a new motor I will change the oil after the first 100 miles then again at 500 miles then at 3000 miles.This is when I change over to Mobil 1 synthetic.If it is a performance motor the oil gets changed after every time at the track.I also use an oil filter cutter to Analise the filter.Also engines with a solid lifter camshaft there is a hole different set of rules for break in.I like the hydraulic roller lifter engines the best.

I have seen a break in related to low speed before and it was related to the transmission (crudely built) Darren gave you a good break in scheme that many fleets use. The magnets are always a good idea.

Many years ago it was normal to run the car at a low speed for the first 1000 miles or 1500km to allow all the parts to bed in. I was told about 1980 that this was no longer necessary as the tolerances and types of material and lubrication had improved greatly. In fact, a colleague from Sri Lanka told me that his company vans had a recurring problem of crankshaft failure (on European made vehicles) and it was attributed to driving too slowly in too high a gear, allowing the engine to run badly as it was too slow.

So should we race away from the start? Maybe, but I tend to treat my engine gently at first, making sure it does not seem overloaded, with occasional higher speed moves to allow the parts that extend to wear in to the "extended" position. This feels right for me and I seem to get very good performance (speed and economy with low noise levels) and do not have any breakdowns.

Ask the guys that run hire companies, you think they run those in..we have a saying here.. the fastest car on the road today is? the new hire car.. So don't believe it.. no way .. this practise comes from a time when manufacturing was a hit and miss activity.. Did any of the persons here ever blue an engine.. I think not, but we did that in the early days not any more.. get in it drive it, it wont break. I always put a magnetic sump plug in to collect the rubbish .. but that is my way of dealing with things..

Even in the old days, when engines were crudely machined in comparison to today's engines, restricting speeds to 40 kph was not recommended -- this is too low for effective break-in. The best approach is to follow the manufacturer's handbook, most of which now say "get in and drive." Bearings in properly designed, manufactured and assembled modern engines do not "break in": the bearings and journals are already finished to a very high standard. There are no "high spots" protruding through the oil film to wear off, etc. Piston rings/cylinder bore fit can improve with a couple thousand miles, but seating the rings requires that the engine be exercised through most of its rev range, because the pistons travel slightly further at high rpm than at low, due to crank flex, etc.

In any event, vehicle speed is the wrong measure for engine break-in, for those who believe in breaking in an engine. RPM would be a slightly better measure, but even it is of little value. If one wanted to minimize load on bearings, for example, then minimizing cylinder pressure would be the way to accomplish that. Thus, avoiding large throttle openings could have some value, as would avoiding running the engine at speeds near its torque peak -- which tends to correspond to relatively low engine speeds.

i agree in the fact to have the engine and vehicle settle for all moving parts to "grind in"; but you will be surprised on that break in of the vehicle or engine in an engine plant or in an assembly plant. those units are pressed to max for performance checks and failure avoidance.

magnets are useful, and changing oil at the first as Dagger suggested, but as someone else replyed, get in the car, and enjoy the ride (don't forget the standard serveces the manufacturer suggest).

The sort of "urban myth" you refer to is mostly a combination of ignorance, imagination and what was once partly true.

Many years ago when engines where hand built and bearings were sized by hand scrapping with the aid of bearing blue, it was important to give the engine an easy time until the "high spots" had worn in. To do otherwise could cause a bearing to pick up and fail. This is not the case today.

More importantly, there is strong evidence to show that a new engine should be subject to quite heavy but very short loads of a few seconds immediately it is warmed up. This is because the high gas pressures from this will bed the new piston rings in better.

Unless you are talking F1 standards, engines do not change shape and relax and move as they get older - the possible exception being some initial relaxation of head gaskets.

It is important that cold engines, new or old, are not overly stressed because engines do change shape as they warm up. Lubrication is also likely to be compromised while the engine is cold.

With the factories all using robots, lasers, and CAD controlled designs, basically all engines are now 'blueprinted' as they are being made.

Saying that iti is not a good idea to dog them by going too slow. You basically can't over rev them because of the rev limiter and you can't load them up fuel wise because of the fuel injection so break-in becomes mearly changing the oil at the first 500 miles and not switching to full synthetic until after the second oil change to facilitate ring seating.

I agree with the oil changes that everyone has mentioned here but not the break in period. I have rebuilt many engines from Ajax pump jack single cylinder engines to automotive and Delaval engines that were 2.5 stories tall and 4 men could fit into the crankcase. I never babied an engine at the beginning of it life and here is why; chrome rings especially, when not run with a sufficient load when new will cause the cylinders to glaze. This glazing will stop the rings from seating correctly causing excessive oil consumption, poor economy and loss of power. On large marine engines if this happen we would actually put an abrasive powder into the intake to attempt to seal the rings. If that failed the engine would be dismantle and de-glazed by replacing the rings and honing the cylinders.

All engines new or rebuilt should be brought to temperature and then loaded to the point at which you expect the engine to operate throughout its life.

One engine re-builder named WAR in the 80's used to have a brake in procedure that was to be followed or the warranty was void. This procedure started by using a drill and long screw driver bit to reach to the oil pump through the distributor shaft access port to make sure the engine was completely flooded with oil. Then the engine was brought to operating temperature and then by using a dynamometer or a road trip accelerate aggressively to high RPM under load (while driving or loaded to 80% of the rated HP) not unloaded, then quickly reduce the load (let of the gas) momentarily and then repeat this cycle up and down for a dozen times. This ensures the rings are forced to the cylinder walls and sealed. The engine can then be brought up to its maximum expected operating load a run indefinitely.

When done correctly the engine will run for many hours or miles of operation without consuming excessive amounts of oil. I have modified this procedure for all types of engines, natural gas, gasoline, diesels both 2 and 4 stroke and have never had an engine fail prematurely.

The seating of the rings is so crucial that some engine manufacturers will not allow you to use products that reduce friction to much during the first 1000 miles. Products like Lucas oil stabilizer or simple straight mineral oils like SAE 40W when used on a new engine will reduce the friction so much that the rings will not seat correctly so it should not be used until the engine has been broke in by aggressive use.

Under loading an engine at the beginning of it life will reduce its life expectancy and reduce the economy and power.

I would follow the recommendations for the company that built the car. In the US 40 Kilometers per hour would be excessively low: most manufacturers recommend driving the car at a variety of speeds for the first 5,000 miles but avoid sustained high speed driving, i.e. over 2,500 RPM. Modern engines are extremely well made and the engine tolerances are so precise that most auto manufacturers recommend the use of 5-20 weight oil. I know nothing about the cars made in India.

i was always told to drive the car/motorcycle during break-in EXACTLY as you intend to drive it later, so that everything is broken-in the way it will be expected to perform.........

having rebuilt many engines of all makes and fuels I find that I need to do the initial break in and have the owner just drive it with a reasonable limit to higher speeds and varied loading so the rings are worked into the cyls well, oil is changed and head/s are retightened at 600 to 1000 miles if head bolts are not new torq to yeild type, when we get a new vehicle we should run it mild for the first 100 miles and then drive it well to set the rings, I had heard of running abrasive like comet cleanser in chromium rings that failed to properly seat but I could never do this myself. I had developed a set for diesel peugeots that had problem with chrome rings, replacing the top ring with a volks bus cast iron flipped over to set the inner chamfer up so compression would push it torwards the cyl wall, this worked very well and lasted longer then rest of the engine, the cyl walls were nitro hardened in these engine and my machine shop hated them, I would run the engine for about 25 miles and turn it over to customer with the understanding that I was to see it at 600 miles or warranty would be voided. have rebuild engines for motorcycles,ultralites,and boats with same expectations, cams are to have moly break in grease on start up and cyls lubed with simple oil on assembly, lithium grease for the crank main and rod journals is all, most important is have a good machine shop, mine did a lot of racing and custom work so they were top notch..
Mitch ret peugeot mech

This has been talked about more than once.

Here's an example.

http://cr4.globalspec.com/thread/60672#newcomments

Take a moment to search the site, and you may find answers you need without opening threads which may duplicate previous postings.

Dear sir; Although I cannot speak for every individual I feel confidant that I can Honestly speak for a considerable quantity of us.

Rest assured that not all of us "auto guys" are that tender with our vehicles new or otherwise. Trust me I've met many guys who say they baby there ride but drive the living snot out of it.

We do tend to try and keep them shiny and straight. But we also have the ability in many cases to often fix what we broke without the "warranty guys" finding out.

So therefore often enough we drive them like we stole them.

"It ain't broke till you can't drive it home."

Aside from that; Considering factory run in time, start of life service, etc most guys aren't too worried especially not enough to drive that slow (40 KPH = 25 MPH. Our speed limits usually start at 30 MPH.) for that long.

Normal highway speeds (88 KPH to 104 KPH) is acceptable for the first 500 miles (800 Kilometers) is generally accepted as normal to a vast majority of people here. (except maybe some of the old timers out there) (you know who you are).

Just make sure you get that first factory oil change at the 500 mile mark or the "warranty guys" will get you.

Even 40 years ago, there was no need to run for 1000 miles at 40 mph.....and certainly not today either!!!

An old mechanic told me about 40 years ago that after rebuilding an engine and making sure timing and everything is correct, to get into the car with a full tank of petrol an empty bladder, something to drink and a few sandwiches. Then drive 250 miles at about 50mph....trying not to stop at all, not using high revs or even too low revs......

These engines all proved to be above standard in both economy and power......but it was a long time ago. Times have changed though....

With modern engines, I do not feel that this is necessary, but I do avoid low and high revs and I do not pull a trailer in the first 5000 KMs ( a little over 3100 miles) either.....I read that in a VW handbook for a TDI Diesel engine about 12 years ago.....the effects if not followed could be high oil usage forever.....I have always followed the rule and always had extremely low oil consumption.

In fact, all the TDI engines I have had (5) all showed a dramatic drop in oil and diesel consumption by 10,000 kms which steadily dropped and dropped till over 100,000 kms, where it steadies out.

I consider a TDI engine to be just about run in by 100,000 kms, not before.....

I have never run a TDI long enough for it to start rising again, but I do know of people who have achieved more than 500,000 kms and have still got a low diesel and oil consumption.....they just run and run if you have good oil, changed at the correct intervals.....

I believe what you are referring to is allowing the piston rings to "break in" to the cylinder walls. The rings need to "seat". Whether this needs to be done depends on the manufacturer of the vehicle in question, because there are some manufacturers that break in the engine before delivery of the vehicle.