why do modern cars not need running in...?
Discussion
Ok, even though I have an engineering background, I was asked a very sensible question yesterday which I was unable to answer satisfactorily .. 
It started of when I was asked why I would have to run in my new T350 when I get her, but then I was asked why you dont have to do that any more with modern cars... Other than mumbling something about "modern materials...", I couldnt differentiate why you had to do one and not the other..!!
Can any of you clever bods out there help me out..??!
(my reputation is at stake here!!)
>>> Edited by mjc on Tuesday 4th May 06:57
It started of when I was asked why I would have to run in my new T350 when I get her, but then I was asked why you dont have to do that any more with modern cars... Other than mumbling something about "modern materials...", I couldnt differentiate why you had to do one and not the other..!!
Can any of you clever bods out there help me out..??!
(my reputation is at stake here!!)
>>> Edited by mjc on Tuesday 4th May 06:57
Hi Guys
As part of my company i have worked in all the major car plants across the country and some aboard. At the end of most production lines the cars are filled with a splash of petrol then manually moved off the line. Most then go to a checking area after that they are then RACED and i mean RACED out of the buildings to the storage areas. I have offen been walking to jobs where a number of cars will be coming along the road in 1st doing about 25-30 revving the balls of it.
So as for running in it will have already been trashed anyway.
Is a motorbike owner i have always ran new ones in as stated in the manual. MCN news did a report not so long back about running in. The bike that was 'run in' as the manual produced less bhp than the one that was trashed from the word go. This was for all bikes tested not just one. There's a link somewhere from google to an american site giving lots of details about running bikes in - they say trash them.
Lee
As part of my company i have worked in all the major car plants across the country and some aboard. At the end of most production lines the cars are filled with a splash of petrol then manually moved off the line. Most then go to a checking area after that they are then RACED and i mean RACED out of the buildings to the storage areas. I have offen been walking to jobs where a number of cars will be coming along the road in 1st doing about 25-30 revving the balls of it.
So as for running in it will have already been trashed anyway.
Is a motorbike owner i have always ran new ones in as stated in the manual. MCN news did a report not so long back about running in. The bike that was 'run in' as the manual produced less bhp than the one that was trashed from the word go. This was for all bikes tested not just one. There's a link somewhere from google to an american site giving lots of details about running bikes in - they say trash them.
Lee
but WHY?!
Is it more true to say that technically ALL new cars should still be run in to allow bedding in of the components and even bore-wear, but that due to modern manufacturing tolerances and materials the necessity has lessened making it almost superfluous in cars where in 90% of cases the engines are going to be relatively unstressed??
Is it more true to say that technically ALL new cars should still be run in to allow bedding in of the components and even bore-wear, but that due to modern manufacturing tolerances and materials the necessity has lessened making it almost superfluous in cars where in 90% of cases the engines are going to be relatively unstressed??
phew! - Deep breath after the above sentance..!! 
When i had a partner back in 2000 we purchased 2 Golf 4motions , i was very careful to run mine in for the first 1,500-KM my partner thrashed the nackers off his from the word go .
Mine has been and still is totally trouble free , his has had 1 replacement engine and was constantly in the shop for problems until the time i sold it , chance ,coincidence , i dont know but it would seem like running in is the thing to do .
Mine has been and still is totally trouble free , his has had 1 replacement engine and was constantly in the shop for problems until the time i sold it , chance ,coincidence , i dont know but it would seem like running in is the thing to do .
Just run them in gently anyway - you know it makes sense.
I spent 1000 miles running my Alfa in and after 8000 miles it stopped using any oil. These cars are, however, renowned for liking a good few drops of the black stuff
and the handbook actually says to check the levels every 300 miles! 
My local dealership refuses to believe that I don't need to constantly top up between services...
Coincidence? Maybe. Don't think so, though.
I spent 1000 miles running my Alfa in and after 8000 miles it stopped using any oil. These cars are, however, renowned for liking a good few drops of the black stuff
and the handbook actually says to check the levels every 300 miles! My local dealership refuses to believe that I don't need to constantly top up between services... Coincidence? Maybe. Don't think so, though.
For those who are interested in the arguement in favour of fully loading an engine from the word go:
www.mototuneusa.com/break_in_secrets.htm
The argument is based on piston ring sealing and the honing patterns used on modern engines. Load is required to hone in the piston rings and bores. Pattern doesn't last very long so high load at earliest point gives good seal.
www.mototuneusa.com/break_in_secrets.htm
The argument is based on piston ring sealing and the honing patterns used on modern engines. Load is required to hone in the piston rings and bores. Pattern doesn't last very long so high load at earliest point gives good seal.
From a man who should know...
John Ravenscroft said:
Tips on Mechanical Sympathy and his engines
RUNNING IN
Most importantly, drive fairly normally. Being too gentle with an engine when running in can be as bad as being too rough.
Although it is important to avoid full throttle or over 4,000 rpm during the first 1,000 miles, occasional bursts (c.5 seconds) of 75% throttle up to 4,000 rpm, will help bed in the piston rings.
FROM COLD
When starting, please be careful not to let it rev straight up so please make sure that you do not give it anything more than a tiny bit of throttle while cranking it over and then lift off as soon as it catches.
Then try to avoid more than 3,000 rpm until the oil (not water) temperature has exceeded 40c, 4,000 rpm until 60c and 7,000 rpm until 80c, If it climbs above 110c, please keep the revs below 5,000 rpm until the oil temperature returns to normal.
Not sure about the speed six but the AJP8 has forged internals which I believe are a different material from the 'run of the mill' car internals.
Certainly this is the case with Skylines, if you buy forged internals these parts have a higher thermal expansion coefficient and shorter piston skirts.
This means they don't fit very well (relatively) in the bores when cold and the short skirts can get scuffed because the piston can move in the bore. However, when warm the pistons expand to fill the bores and all is well. Hence no thrashinf from cold.On a healthy engine I reckon this is where the majority of oil usage occurs, at startup.
Certainly I was told that if I upgraded my engine internals then my oil usage would go up for this very reason.
Rob.
Certainly this is the case with Skylines, if you buy forged internals these parts have a higher thermal expansion coefficient and shorter piston skirts.
This means they don't fit very well (relatively) in the bores when cold and the short skirts can get scuffed because the piston can move in the bore. However, when warm the pistons expand to fill the bores and all is well. Hence no thrashinf from cold.On a healthy engine I reckon this is where the majority of oil usage occurs, at startup.
Certainly I was told that if I upgraded my engine internals then my oil usage would go up for this very reason.
Rob.
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