We have all heard stories of vehicles that have done enormous distances without ever needing an engine overhaul.
The following one comes from the Internet, and it seems authentic because a well-known oil company can apparently vouch for its accuracy.
In 1995, William White from Lawrenceville, Georgia, in the US, bought himself a Chevrolet bakkie for delivering bulk newspapers to several cities in North Carolina and Tennessee. White had a far-flung round of deliveries. In fact he covered about 1280km on every trip.
He also followed a very strict maintenance schedule: After every four trips he took his bakkie to the local "fast lube" to have the oil changed, always insisting on the same oil.
On August 29 2001, the bakkie's odometer turned over to 1,6million kilometres as White once again drove into his favourite fast lube, where this time, oil company officials were waiting to take possession of the million-mile pick-up in exchange for a new one.
The engine of White's intrepid Chev bakkie was then taken apart and studied by technicians to determine how much wear it showed. The report by a senior research engineer stated: "The million-mile truck engine is in excellent mechanical condition. The engine exhibits very minimal wear and is very clean in the category of sludge and varnish."
The cylinder bore measurements averaged 4,001 inches whereas the factory specifications for new engines stipulated a bore diameter of between 3,9995 and 4,0025 inches.
In fact, the wear was so minimal that about 12percent of the original crosshatch honing marks were still present.
So an engine can last, without any significant wear, for more than 1,5million kilometres, which is more than most people will cover in a lifetime.
The harsh reality, however, is that the average owner can be thankful if his vehicle does 300000km without an engine overhaul.
What did William White, and others who got more than a million kilometres from an ordinary car or bakkie engine, do to make their engines last so long?
The first thing is very frequent oil changes. White took his Chev bakkie for an oil change every 5000km.
In the space of 5000km harmful contaminants, unburnt fuel, moisture and blow-by gases, simply don't have time to accumulate in the oil. Hence, the absence of sludge and varnish.
If you are going to change the oil every 5000km, it doesn't make sense to buy the most expensive high-tech oil on the shelf, unless the engine maker specifies such an oil. A good-quality, multigrade mineral oil is quite good enough for ordinary engines.
The second thing is to avoid short trips and stop-start operation as much as possible.
An engine used for short pick-up and delivery runs in a large city will have a much tougher life than one used mostly for long-distance highway trips. In this respect the million-mile Chev engine was lucky- it operated almost exclusively under the most favourable conditions an engine can wish for.
The engine in the typical mom's taxi, on the other hand, works under cruelly adverse conditions - its oil seldom gets hot enough to drive off the contaminants received during the first few minutes after a cold start-up, and it faces prolonged periods of idling in traffic.
Idling, incidentally, is unhealthy for an engine, which makes it all the more inexplicable why some drivers leave the engine to idle after starting in the morning "to warm up".