Replacing a diesel engine's turbo costs a lot of money.
How should a diesel car's owner drive, park and take care to insure that he/she gets the maximum km/miles out of his/her car's turbo?
I would say a Turbo is no more likely to fail than other components on your car such as engine or gearbox. A Turbo on a diesel engine is likely to last even longer than on a petrol engine due to lower temps, rpm and loads.
Turbo design and engineering has come a long way since the 1980's. Assuming it's not a modified or a competition car, the Turbo on any car built in the last 30 years should last as long as any other component.
Caveat: There will always be examples of a particular make/model that has a poor reliability of a particular part such as a engine, gearbox or turbo. That doesn't mean they're all bad. It means that one is bad. Read reviews about the car you want to buy and make up your own mind if you think that particular car has reliability issues.
In the past the weak point of turbo was heat and lubrication. They get so hot that they can cook the oil when turned off. Improvements in cooling through materials and design and even oils mean this is much less of an issue.
Just as for any other component on your car, regular maintenance should ensure it has a long life span. Probably the most useful thing you could do is ensure that it is serviced at the recommended intervals and oil and filters as changed as specified. The contra to this is: If you neglect maintenance you are likely to shorten the lifespan of your engine.
As for driving techniques: The same kind of advice applies. If you treat your car nicely it will last. Let the engine warm up before working it hard. Try to avoid over-revving, over-loading or over-heating the engine. Drive smoothly.
As a precaution, if you have been driving the vehicle hard or on a long trip driving it gently for the last few miles or letting it idle for a minute or two to cool down may be of benefit. You can see rally cars still do this today.
If you consider the points above, and you drive normally and service your vehicle regularly this should never be an issue.
I think turbos may have a unfair reputation for reliability due to their association with high performance cars such as rally cars. These cars are driven to the absolute limit, big horsepower, high boost, high rpms and temps. Under those sorts of conditions everything suffers, and mechanical failure rates are higher. An everyday car is unlikely to be subjected to that kind of treatment, and is therefore likely to last much longer.
Axleaddict.com shares 5 tips on how to extend turbo life. Here they are:
- Regularly Scheduled, Synthetic Oil Changes
On turbos, it is recommended to change the oil every 8,000 km (5,000 miles) to preserve the system. Fully synthetic oils are also the best, because they protect better at high temps.
- Warm It Up
It's great to have the right oil, but if the oil isn't covering everything, it won't help as much as it ought to. Before taking off, let your motor warm up a bit.
- Cruise Right, Cruise Light
Don't run your car at max all the time; maintaining the boost/vacuum gauge between 10-15 inches of mercury should hold your engine in top gear. You're not anywhere close to using the turbo, so you reduce wear.
- Cool It Down
After you've been driving hard or using it on the highway for a couple hours, spend a minute or two to allow the engine oil to cool down. This will prevent the oil from cooking on in places where it is extremely hot and stops moving.
- Work the Gears, Not the Turbo
If you can select which gear you're in, using a lower gear for hills and passing can preserve your turbo from a lot of work. Your engine is more efficient at lower RPM's where the turbo isn't running. Your car has more than just the turbo: don't just use the turbo.
Here is a previous post that may provide additional information related to forced induction.