Ratbag
Administrator
- Joined
- Jan 1, 2012
- Messages
- 7,483
- Location
- Bayside, Melbourne, Vic
- Car Year
- MY06, MY10
- Car Model
- Forester SG & SH
- Transmission
- 5MT/DR & 4EAT Sports
Gidday All
Modern cars and engines are made to tolerances that would have astonished even the finest car makers in the world a mere 50 years ago.
Introduction:
However, while modern bearings (etc) are brilliantly made, and like polished glass to the touch, at a nearly molecular level the surfaces are as rough as guts. There are huge "mountains" and "valleys" if examined under a microscope at around (say) 2,000x.
Running-in ("breaking-in" in US English) is the method used to smooth out these huge mountains and valleys without wrecking the engine (etc) in the process. I only wish I had some photomicrographs to demonstrate these things.
Many makers have stated that it is unnecessary to run-in a modern car. I could not disagree more. It bothers me that some people will believe this, particularly if they are younger, and not used to the essential running-in process that us old lags were brought up with!
Running-in an engine is only part of the deal. Running-in the diff/s and gearbox as well as brakes, clutch, etc are all part of the deal. Diffs are particularly hard to "work". The stuff below is based on running in a manual car. One would need to vary the procedure a bit for cars with auto transmissions, but should still be achievable with an AT. Set the AT to "Sports mode" rather than just letting it change gears whenever the load is slightly reduced.
Brakes and clutch should always be treated carefully after changing pads, machining discs, replacing clutch plate etc, at least for the first 100 kms or so.
To achieve a good run-in of the entire car, I tend to pick it up from the dealer then take it for a long drive - about 250-500 miles is good (400-800 kms). This should be on an open road (no restrictive speed limits) with little to no traffic. It should have plenty of curves, and be neither steep nor flat. The flatness is not a real problem, it's just that it is hard to vary the load properly unless the road helps you to do this. A relatively curvey road is pretty much essential, as this is what helps the diffs to bed in properly, and encourages changing gears a lot.
This is what I have done since I had my first new car, over 40 years ago:
Do NOT use cruise control ...
I tend to keep between 2500 to 4000 revs for the first 500 kms (and avoid fifth gear entirely - far too easy to let the revs drop … ) .
2500 to 4000 with the occasional short squirts to 4500 to 5000 (a couple of seconds) for the next 500 kms. Still no use of fifth. First service (oil change and filter).
2500 to 4500 revs for the next 1000 kms, with occasional squirts to 5000 lasting a couple of seconds at a time. Use fifth when cruising on a freeway, etc; but keep revs above 2500 at all times.
After the first 2000 kms, allow some use of lower revs (but don't allow engine to labour - fat chance, LOL! ) and fifth during normal suburban driving. Don't exceed 5500 revs, and then only for shortish periods. Keep this regime up until the donk has about 5000 kms on it.
Change oil and filter again at 5000 kms. Then normal servicing per usage.
This sort of run-in regime is what I would advise for "normal" use.
What this does is:
Allows the molecular level peaks and troughs on all contact surfaces to break off (if "large"). The broken off bits are removed at the first oil and filter change at around 1,000 kms.
Allows "small" molecular level peaks and troughs to flow to level.
The above will achieve an engine that has good performance and fuel economy, combined with longevity. If done carefully, the engine should not use oil; or will use a very minimal amount between normal services.
Running an engine in "slow" causes the peaks and troughs to flow completely. The peaks do not break off. This means that the engine tolerances will always be "tight". This translates into (relatively) poor fuel economy and performance; but great longevity with zero oil use.
Running an engine in "fast" causes all the molecular peaks to break off. The engine will always be "loose". This translates into an engine that gets great fuel economy and performance; but will use oil and not last as well as the "normal" engine.
The above thoughts are a result of careful observation of engines and running in practices of both myself and others over some 50 years.
Just a few thoughts on this subject, FWIW. Hope it helps some.
BTW, I never buy "Demonstrator" cars with a few thousand kms on the clock. These cars have had the very worst sort of running-in, if one can call it that!
Multiple drivers who do not have a clue how to drive the car, let alone any new car. After all, they won't be buying that one ...
[EDIT] I lost this post while writing it (my browser hung ... ), so had to recover it from a screen dump. The occasional strange error is due to Acrobat Pro, "re-interpreting" the screen dump using its text recognition engine. It works remarkably well when one thinks about what it is actually doing!
[end edit]
Modern cars and engines are made to tolerances that would have astonished even the finest car makers in the world a mere 50 years ago.
Introduction:
However, while modern bearings (etc) are brilliantly made, and like polished glass to the touch, at a nearly molecular level the surfaces are as rough as guts. There are huge "mountains" and "valleys" if examined under a microscope at around (say) 2,000x.
Running-in ("breaking-in" in US English) is the method used to smooth out these huge mountains and valleys without wrecking the engine (etc) in the process. I only wish I had some photomicrographs to demonstrate these things.
Many makers have stated that it is unnecessary to run-in a modern car. I could not disagree more. It bothers me that some people will believe this, particularly if they are younger, and not used to the essential running-in process that us old lags were brought up with!
Running-in an engine is only part of the deal. Running-in the diff/s and gearbox as well as brakes, clutch, etc are all part of the deal. Diffs are particularly hard to "work". The stuff below is based on running in a manual car. One would need to vary the procedure a bit for cars with auto transmissions, but should still be achievable with an AT. Set the AT to "Sports mode" rather than just letting it change gears whenever the load is slightly reduced.
Brakes and clutch should always be treated carefully after changing pads, machining discs, replacing clutch plate etc, at least for the first 100 kms or so.
To achieve a good run-in of the entire car, I tend to pick it up from the dealer then take it for a long drive - about 250-500 miles is good (400-800 kms). This should be on an open road (no restrictive speed limits) with little to no traffic. It should have plenty of curves, and be neither steep nor flat. The flatness is not a real problem, it's just that it is hard to vary the load properly unless the road helps you to do this. A relatively curvey road is pretty much essential, as this is what helps the diffs to bed in properly, and encourages changing gears a lot.
This is what I have done since I had my first new car, over 40 years ago:
Do NOT use cruise control ...
I tend to keep between 2500 to 4000 revs for the first 500 kms (and avoid fifth gear entirely - far too easy to let the revs drop … ) .
2500 to 4000 with the occasional short squirts to 4500 to 5000 (a couple of seconds) for the next 500 kms. Still no use of fifth. First service (oil change and filter).
2500 to 4500 revs for the next 1000 kms, with occasional squirts to 5000 lasting a couple of seconds at a time. Use fifth when cruising on a freeway, etc; but keep revs above 2500 at all times.
After the first 2000 kms, allow some use of lower revs (but don't allow engine to labour - fat chance, LOL! ) and fifth during normal suburban driving. Don't exceed 5500 revs, and then only for shortish periods. Keep this regime up until the donk has about 5000 kms on it.
Change oil and filter again at 5000 kms. Then normal servicing per usage.
This sort of run-in regime is what I would advise for "normal" use.
What this does is:
Allows the molecular level peaks and troughs on all contact surfaces to break off (if "large"). The broken off bits are removed at the first oil and filter change at around 1,000 kms.
Allows "small" molecular level peaks and troughs to flow to level.
The above will achieve an engine that has good performance and fuel economy, combined with longevity. If done carefully, the engine should not use oil; or will use a very minimal amount between normal services.
Running an engine in "slow" causes the peaks and troughs to flow completely. The peaks do not break off. This means that the engine tolerances will always be "tight". This translates into (relatively) poor fuel economy and performance; but great longevity with zero oil use.
Running an engine in "fast" causes all the molecular peaks to break off. The engine will always be "loose". This translates into an engine that gets great fuel economy and performance; but will use oil and not last as well as the "normal" engine.
The above thoughts are a result of careful observation of engines and running in practices of both myself and others over some 50 years.
Just a few thoughts on this subject, FWIW. Hope it helps some.
BTW, I never buy "Demonstrator" cars with a few thousand kms on the clock. These cars have had the very worst sort of running-in, if one can call it that!
Multiple drivers who do not have a clue how to drive the car, let alone any new car. After all, they won't be buying that one ...
[EDIT] I lost this post while writing it (my browser hung ... ), so had to recover it from a screen dump. The occasional strange error is due to Acrobat Pro, "re-interpreting" the screen dump using its text recognition engine. It works remarkably well when one thinks about what it is actually doing!
[end edit]
Last edited:
.
:lol: ... 
