[A4] Oil Break In.... (Long)

[Paul W. Henne]

Nicholas Stock wrote:

>http://www.mototuneusa.com/break_in_secrets.htm
>A friend sent me this link....any thoughts?
> Nick
>  
>

Like everyone else, I may have something to contribute here also.  I 
bought my A4 with 300+ miles on it (it had been transferred from a 
dealer in CT), and used the procedure below to break it in, starting 
from the 300+ mile mark.  At 145,000 miles, my car uses hardly any oil, 
idles so smoothly sometimes you can hardly tell it's running, and even 
my mechanic (an Audi tech who does work on the side) said with the chip 
switched off using factory programming it seems noticeably quicker than 
the other 1.8Ts he has driven.  So obviously there is more than one way 
to skin this cat.

What "Motoman" says about modern manufacturing techniques probably does 
have a good bit of merit, so I don't know how well the procedure below 
could be applied to a more modern engine than mine.  But the technique 
below does seem to be a lot easier on the engine, and has just as much 
technical info to back it up.  It does seemed to have worked very well 
for both for my A4 and it's predecessor (a '92 Saturn SL2 that was 
demonstrably quicker than most, and also used very little oil).  
Feedback is certainly welcome.

Paul

Ben Slosser's guide to 4-stroke engine break-in:

[Adapted for '98 Audi 1.8T by Paul W. Henne. I basically doubled the 
mileage amounts and adjusted the first oil change recommendation, which 
had been 3000 miles.]
                
The Practice.
  For the first 100 miles, only take short trips of 15 minutes.  Do not 
rev above about 3500 rpm.  Use full throttle in short (2-3 second) 
bursts at low rpms (say 2500) - 5th gear on the freeway is ideal for 
this.  Do not do more than one full-throttle burst in the same 3-minute 
period.  Avoid driving for more than 2-3 minutes at the same rpm - if 
you are on the freeway, vary your speed and alternate between 5th and 
4th gears.
                
  From 100-1000 miles, increase the peak RPM you reach by 100-200 rpm 
each time you drive the car (but don't go higher than redline).  Do not 
rev to your new peak under heavy throttle; instead, let the engine drift 
up to the rpm under light load.  For instance, pulling away from a 
stoplight, leave the engine in first and accelerate lightly until you 
reach the desired RPM, then shift.  Continue the full-throttle-burst 
procedure.  Do not rev the engine high under full throttle, and do not 
do either the peak-revving or the full-throttle procedure more often 
than once a minute.  Avoid driving for more than 5 minutes at any one 
rpm - again, alternating between two adjacent gears and varying your 
speed will work.
                
You will notice that each time you reach a new peak rpm, the engine will 
be quite loud at that rpm, but after a few runs up it will quiet down. 
This is a sign that the break-in is proceeding well.  You will want to 
have revved the engine to redline a few times by the time you reach 1000 
miles. 
                
  From 1000-5000 miles (the extended break-in) you can operate your 
engine fairly normally.  Most of the work is done.  You should still run 
the engine at higher RPMs on a regular basis (assuming you don't in the 
normal course of driving ;-) ) and you should avoid prolonged 
high-speed/high-stress operation, like racing or cruising at 135 mph.  
Be sure to change the oil at 5000 miles (1.8T) or whenever your first 
scheduled service is due [but no earlier; due to many reports of 
excessive oil consumption from people who changed their oil before the 
first recommended service interval -- something which was peculiar to 
Audi engines at that time. -Paul].

  From 5000 miles onward, your engine is considered broken in.  It will 
probably continue to "loosen up" a bit over the next 5000-15000 miles, 
so look for a small increase in gas mileage.  Other than that, your 
engine is now ready for a long and productive life.  Enjoy!

***** BEGIN TECHNICAL SECTION *****
               
[Some of this is what I remember from articles I have read and 
discussions. I cannot vouch for the complete accuracy of what follows, 
but I believe it to be essentially correct.  If you *must* flame me, 
please do so in private unless you think I've made a mistake which 
everyone need to know about to avoid doing something unpleasant to their 
car -B.Slosser]
                
The Theory.
  The primary goals of engine break-in are: 1) achieving a good seal 
between the piston rings and cylinder walls, and 2) allowing the engine 
to operate correctly throughout its RPM range. The major enemy during 
the break-in period is localized heat buildup, mainly in bearing 
surfaces (most notably the crankshaft bearings). 

Initial state:               
  When the engine is machined at the factory, many wearing surfaces 
(places where parts rub against each other - cylinder walls, bearings, 
etc) are purposely machined more roughly than they could be.  The reason 
for this is that it allows the engine to complete the 
machining/polishing as it operates, thus allowing for the individual 
variations inherent in any manufacturing process.  This wearing process, 
when complete, produces parts which will fit together with very tight 
tolerances.  However, the process also involves a great deal of 
friction, which in turn means a great deal of heat.  As metal parts 
heat, they expand slightly.  If the expansion goes beyond a certain 
point, the parts will tend to bind with and/or score each other.  This 
must be avoided.

[To put this in plain english, the parts which rub against each other 
are left a bit rough, and as the engine runs the parts will scrape 
against each other until they wear down a bit and have a proper fit.  
While they're still in the process of scraping, they can get very hot; 
if they get too hot, they will damage each other in a permanent way.]

Since this sort of heat buildup is very localized, it will not show up 
on the engine temperature gauge.  Therefore, it is important to operate 
the engine in such a way that the heat buildup will not reach a 
dangerous level.  More on this later.

Stress and Variation:
  Although the engine parts are metal and, as a rule, quite rigid, they 
are still subject to slight deformation when stress is applied.  The 
largest stress in a piston engine is that produced by reciprocating 
parts.  The forces involved increase as the square of the RPM.  Any 
deformation will necessarily involve a change in some tolerances inside 
the engine.  Thus, in order for the engine to operate properly over a 
range of RPMs, it is important that it be exercised over this range 
during the break-in process so that the wearing parts will experience 
the range of tolerances they will be subjected to during normal 
(post-break-in) operation.  Further, for the wearing surfaces of 
reciprocating parts (most notably the piston ring/ cylinder wall 
interface) operation at a single RPM for an extended period of time will 
cause the machining process to progress significantly further within the 
confines of the part's range of travel without progressing at the point 
just outside that range, thus building up a small ridge of metal just 
above the point of maximum excursion.
                
[In order for your engine to run well from 1000 to redline, you need to 
operate it at all those rpms while it is breaking in.  If you don't,   
the parts won't be used to working at the rpms you neglected, and they 
won't work as well at those speeds]

Piston Ring Sealing:
  The seal between the piston ring and the cylinder wall is crucial to 
getting good economy and performance from the engine.  A bad seal will 
allow more blow-by, reducing the amount of power the engine can produce 
with each power stroke and thus reducing both its horsepower and fuel 
economy, as well as allowing combustion gasses to get into the crankcase 
and contaminate the oil AND allowing oil to get into the combustion 
chamber and be burned,  producing the characteristic 
blue-smoke-from-the-tailpipe syndrome (note that oil can also get into 
the combustion chamber via the valve stem guides, but that's not 
something we can do much about during break-in). 

The key to getting a good piston ring seal is high combustion chamber 
pressures.  High combustion chamber pressure is produced under hard 
acceleration; also, the lower the RPM the longer that pressure is 
maintained during each power stroke.  SO - to get a good piston ring 
seal, hard acceleration at low RPMs will give the best results.  Since 
hard acceleration also produces more heat and more stress (leading to 
friction and still MORE heat), it should only be used in brief bursts, 
followed by a couple of minutes of "normal" low-stress operation to 
allow the heated parts to cool down.
                
Localized Heat Buildup:
  As previously mentioned, wearing parts will produce inordinate amounts 
of heat as they polish each other.  This produces local points of 
intense heat inside the engine, with temperatures far higher than the 
engine as a whole (which shows up on the temperature gauge) or even of 
the surrounding parts.  The most susceptable points in an engine for 
this kind of heat buildup are the crankshaft bearings, which must 
withstand enormous stress and pressure.  If the bearings are allowed to 
get too hot, they will expand to the point of scoring each other or 
(*gulp*) binding, producing a spun bearing.  During the initial stages 
of engine break-in, there is no satisfactory way of keeping these 
bearings cool during even mild engine operation except to turn the 
engine off after every 10-15 minutes of operation and allow the bearings 
to cool down. 

The theory I have outlined about should now be sufficient to explain the 
"practice" section of the break-in instructions.  For the first 100 
miles, keep the rpms low and the trips short to minimize the stresses 
and heat buildup in the bearings, and use short full-throttle bursts to 
seal the piston rings.  From 100-1000 miles, gradually increase the RPMs 
to allow the wearing surfaces to correctly mate, and continue using 
full-throttle bursts to ensure ring sealing.  Use cooling periods (the 
3-minute rule) to minimize the heat buildup produced by the high RPM 
operation and the full throttle bursts.

---

-- 
Paul W. Henne <MarylandGuy_42 at yahoo.com>  

"Good judgement comes from experience; and experience, well, 
that comes from bad judgement." -Anonymous

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