Ignition timing was set to reduce engine load, carburettor air/fuel ratios were altered and valve clearances needed to be reset after a short run while high engine revs and excessive vehicle speed were avoided at all costs.
Exhaust tail pipes were also monitored closely to ensure the blue smoke slowly disappeared which was a sure sign the engine was settling down nicely. Even during the engine reconditioning rebuild process, the "tighter" the engine was the better, and using a fairly heavy hammer handle to drive the pistons into the engine bore was considered standard practice.
No doubt there are still some engines that do still require that special love and attention but for the power units fitted into the majority of the fleet these days, things have definitely changed.
Due to the ongoing advancement in engine design and the use of superior materials and lubricants plus the improvement in fuel quality, the internal combustion engine has become a lot more reliable, environmentally friendly, more fuel efficient and suffers from less internal wear than ever before.
Service intervals are being stretched further and further, which is also a sure sign that the engines will tolerate longer periods between oil changes without suffering undue damage or wear.
On-board electronic wizardry has also played a massive role in ensuring engines perform at their peak in all conditions and straight out of the box. Fuel mixture, ignition and valve timing are all taken care of automatically and are constantly being altered based on various conditions such as vehicle and engine speed, temperature and load.
The modern engine is far from bullet-proof however and some may say it's a lot less forgiving than it ever was. For example, it doesn't take much of an overheating problem to cause major internal damage these days, while fuel quality is vital - especially so with diesel engines.
Anyway, as far as running-in techniques go, on a brand new engine it's more about using common sense than doing anything too dramatic or specific.
You wouldn't drive out of a new vehicle showroom and immediately hook up your boat or caravan or drive on the limit of the rev counter for example.
New engines do need a little time to settle down but it's more about gaining the optimum in performance and fuel economy rather than anything else.
Best advice is to follow the recommendations of the respective new vehicle franchise and to take the time to read through the owner's manual to make sure there are no special requirements for your particular vehicle or the environment in which you drive.
For example, with some diesel engines, clogging of the particulate filter (which traps diesel soot from the exhaust gas) can be due to lots of short trips around town on a cold engine.
Often the recommended "fix" is to get the engine up to operating temperature for a lengthy period (such as a long drive at highway speeds) so the soot can be burned off the filter. This can become an ongoing exercise.
Regardless of fuel type, if you do have any concerns about excessive fuel or oil consumption after purchasing a new vehicle, then it's very important that they are taken seriously by the franchise dealer and you should insist on accurate records being kept and the situation monitored over a reasonable period.
If you own an older, tired vehicle that requires a major engine overhaul, then probably the best advice is to ensure the job is given to a reputable repairer.
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