One of the biggest problems buying a second hand diesel-engined car from the modern era (common rail, DPF, turbo) is that even if they are serviced on schedule and every 10-12.5k/1 year, the buyer rarely knows HOW that car was driven for the mileage driven - for lower mielage examples, it could lots of short trips from cold or less numbers of longer journeys, which are polar opposite as regards keeping the DPF in good nick.

The same goes (for the turbo) if any of the previous owners did not idle the engine before switching off after a long drive and/or when towing. They also don't know if that owner used regular diesel or super.

At least with petrol-engined cars (not including high performance models), they are affected less in such regards (perhaps excepting some for the turbo) as they aren't used or work in the same way as a diesel-engined car.

I think that if you push a diesel hard and give it lots of revs the turbos wear out quickly and are in more use than their petrol equivalent.

Is this based on anything in particular or just your opinion?. A turbo being less reliable in a diesel than in a petrol is not something i've heard before. Turbo's obviously will wear out, but i'm not sure that the fuel source would have anything to do with that. How the car is driven on the other hand, would have a lot to do with it!.

Surreydriver makes some interesting points.

There was a time when turbo failure on large lorries was unheard of, and at much higher road speeds than current in the UK, where nowadays they are almost a regular failure, yes even on those makes that have the 'reputation', in some cases undeserved from what we are finding out in practice.

Not only did owners/operators have much more regular service regimes, i think the main difference is that no one was obsessed with engine idling for more than a few seconds as they are now, vehicles were started from cold and allowed to warm for a few minutes before driving off, and no lorry driver of the period worthy of the job would dream of shutting an engine off until the turbo had cooled down sufficiently.

Vehicle makers actively encouraged good practices (not 20 years ago lorry handbooks instructed the driver to start the engine and warm through before driving off), and they didn't make fantastic claims about how some sensible idling was no longer necessary due to a variety of new technologies, ignoring failure rates.

I wonder how many owners/drivers of Diesel cars who observe a bit of mechanical sympathy, not driving slowly as such but allowing the vehicle to get up to temp and down again, and keep them decently serviced with plenty of good oil in the sump, still run Diesels without any of the problems that crop up on these pages?

Just out of interest i've never taken a blind bit of notice of these new approved methods, the engine still gets warmed and it gets some idling time before shutdown, and in what must be close to some 4 million miles in mostly turbocharged Diesels i'm yet to have a turbo failure in any of my work vehicles or my own.

Edited by gordonbennet on 09/09/2019 at 09:39

Volvo 2.4 58 plate and 130k is going strong as ever with a mixture of local and long runs. Mercedes 2.2 of a 12 plate with turbo (s) and 53k with the same use as above so far has been fine. It's the other bits that do me at mot time, tyres, ball joints, discs and pads etc. despite regular servicing and moderate driving habits.