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What are you trying to do, destroy the value of used diesel cars and then snap them all up?
We have 2 diesels in our household, both have dpf's, one has a dmf. Forget the dmf bit as some petrols have them fitted. We save about £1000 in fuel bills a year using diesels instead of using petrols,, save probably another £200 a year in RFL costs. Servicing is near enough the same, total saving £1200 a year. Add to that modern diesels are a much better drive than the gutless petrols most manufacturers sell, quite like the small turbo petrols but they are not cheap.
Over 5 years we expect to save £6000. My car was £300 more than the equivalent gutless petrol I tried, the wifes £1000, expect to get 1/2 that back when we PX, additional cost £650, saving reduced to £5350 over 5 years.
If we have have to spend £5350 extra in repairs in 5 years we break even but have had a better drive.
Its a risk I will continue to take. We are not chickens or sheep, we have the capacity to think logically and take our own rational decisions rather than panicking.
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Not sure of the logic being applied by the garage here in terms of servicing. If he does mean dmf and dpf then I think some dpfs need some service attention (refilling some fluid) but that aside they arent serviced are they? DMF are not serviced at all. And you can't avoid misfuelling errors by a service. So if he was to trade all diesels it might make sense, depending on how seriously you view the modern diesel issues, but I don't follow the service argument.
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DPF diesels require (usually expensive) low ash oil. Skimp and you get problems and with SOGA the dealer could be saddled with a bill for DPF replacement shortly after selling, goodbye proft and some.
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What are you trying to do, destroy the value of used diesel cars and then snap them all up?
No,
I too fell for the magic of higher mpg, but found out that the 6 extra oil changes in 2 years cost me hundreds, on top of the servicing. I see and read in this forum and others about people having expensive repairs on dmf fitted cars, my neighbours vw, dmf clutch replacement nearly £900 at an indie, other neighbour £7000 of repairs on a 4 year old vauxhall diesel, surely better to bin the car.. There are good and bad sides to all cars and people will have different experiences too.. I think though that the dealer is entitled to protect his reputation and his profit margins too. The diesel i had returned about 40mpg +/- 3mpg and now the petrol is doing 35+/- 2 mpg so with the costs of servicing a lot lower and petrol abit cheaper, and the fact that the car was a demo low mileage unfashionable model means that i think i got out in time and saved a bit against the list price. As it happens my insurance is lower, ved lower, but that isn't the point i was making, which was really buyer beware buying ANY used car with dmf/dpf.. Go to technical questions and read the posts about people buying these cars used andd after afew months oof!
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If you have a genuine DPF regen problem in less than 100,000 miles then you bought a car with an engine that was hopelessly oversized for your needs as opposed to your aspirations.
DMF is a slightly different matter. Petrols do have 'em, but they put less stress on them than diesels. You can ease the stain on the DMF by using a few revs to pull away rather than lazily letting the clutch out and letting the governor maintain idle speed. Look after the DMF and it should last as long as the torsion springs in a conventional clutch assembly.
Let's just wait a while and see how these little turbo petrols fare before writing off diesel...
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I think it is a case of 'horses for courses'. Too many people have jumped on the diesel bandwagon i.e. people doing modest mileages, often involving short hops around town. I used to do a big commute (100 miles a day) where a diesel was ideal, but now do less than 10k per year and would not dream of getting a diesel.
Modern diesels have become very complex, but they still offer considerable advantages for some. Of course the real problem buying secoundhand is that you don't know if the diesel your buying has recently been subjected to abuse i.e. a driving pattern likely to cause DPF/DMF issues.
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This is true. But why do people consider modern petrols to be less 'complex'. than modern diesels? You have to do a hell of a lot more with to a petrol to get big mpgs than you do with a diesel.
We have to compare apples with apples.
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"But why do people consider modern petrols to be less 'complex'. than modern diesels? You have to do a hell of a lot more with to a petrol to get big mpgs than you do with a diesel.
We have to compare apples with apples."
I think you're missing the point. If we're talking about reliability and overall running costs in diesels as opposed to petrols that, it seems to me, is comparing apples with apples. "Complexity" - however you define it - doesn't come into it; people are just remembering that diesels used to be mechanically simple, mainly agricultural or commercial machines and they're not like that any more. Petrol engines have not changed as much, but of course they also are more complex than they were.
Speaking for myself, I gave up on diesels over twelve months ago and have seen nothing since that makes me regret my decision.
Edited by FP on 29/09/2012 at 13:52
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>> rather than lazily letting the clutch out and letting the governor maintain idle speed.
You omitted 'in second'.
I had diesels for ten years before a new injector pump cost me over £1300.
I've now a couple of petrols that clock up less (fewer?) miles than 10K a year between them.
I still miss the 'grunt' of a turbo diesel.
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I've had my Yaris diesel 6 years. No DNF,no DPF. Short journeys mainly . No problems.
But I do 4,000rpm at least once a week driving hard...
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But I do 4,000rpm at least once a week driving hard...
And please tell me what that achives. Had diesels since 1996, never had a problem and never done that.
Never seen it written in the manual to rev the nust of a petrol or a diesel.
Its been said before by many posters, use it normally and you will be OK. Us it for 2 mile school and shop trips and you are inviting disaster.
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Its been said before by many posters, use it normally and you will be OK. Use it for 2 mile school and shop trips and you are inviting disaster.
But if that is what you are using it for, the italian tune up is necessary to keep the car running sweetly.
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But if that is what you are using it for, the italian tune up is necessary to keep the car running sweetly.
The "Italian Tune Up" may have had a place in the 60's when cars had carburettors, manual chockes and the petrol was c r a p. With modern cars you do not get the build ups that need clearing out (if they ever did). All you are doing is wasting fuel.
Back in the 60's (and into the 70's) cars needed a decoke every 30,000 miles in some cases, how often do you hear about decokes today.
Show me a manual where it tells you to do such a thing.
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It also has a place in the running a PSA diesels with DPFs using EOLYS fluid, to get the DPF hot enough to intiate the regeneration cycle.
in most cases the regeneration process is activated by the exhaust pipe getting hot which is achieved by getting the engine speed up. The best way to ensure a regeneration is successful, is to maintain the engine speed at 2500 rpm for at least 15-20 minutes. Driving along a dual carriage way, for example, at 50 mph and stopping for roundabouts won't be achieve a successful regeneration because a constant high engine speed needs to be maintained for a successful regeneration. He also adds that manufacturers should be advising drivers to drive for a sustained period of time and focus on getting their revs per minute up instead of focusing on the speed.
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the regeneration process is activated by the exhaust pipe getting hot which is achieved by getting the engine speed up.
No, it isn't. This is an age old myth, that everyone believes-except those who use exhaust pyrometers. If a diesel engine is producing 20 hp at 1500 RPM, it will have a higher EGT than 20hp at 2500 RPM. Ther eason being that the engine will be running much leaner at 2500 RPM hence EGTs are much lower-even though is less time available for heat transfer.
The 'italian tune up' is quite useful in that it keeps things moving throughout their entire operating range. If you never rev the engine above, say, 2000 RPM, the oil pressure relief valve never opens, the turbo vanes/wastegate never fully open. Piston oil jets may never operate.
Parts that should move and don't tend to have a nasty habit of not moving when they are eventually required to!
I also worry about ridges forming at the top of the cylinder bore. Using the full range of engine speeds periodically prevents this from happening.
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The 'italian tune up' is quite useful in that it keeps things moving throughout their entire operating range. If you never rev the engine above, say, 2000 RPM, the oil pressure relief valve never opens, the turbo vanes/wastegate never fully open. Piston oil jets may never operate.
Parts that should move and don't tend to have a nasty habit of not moving when they are eventually required to!
I also worry about ridges forming at the top of the cylinder bore. Using the full range of engine speeds periodically prevents this from happening.
Unthrottled, your posts are always logical and clearly based on wide experience and technical knowledge. I agree with your point that using the full range of revs ensures vanes etc don't stick, but I don't see how this stops ridges in cylinder bore tops - surely the pistons and rings stop in the same position at all speeds? (Conrods and crank webs can't stretch that much?)
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No, con rods do not stretch much, but when you factor in bearing clearances, differential heat expansion betwen parts etc. you end up with a small, but tangible difference in where the piston finishes at TDC. This is why engines have to be built with a minimum clearance between the piston and the cylinder head.
The top of the bore is always poorly lubricated so I don't like the idea of a ridge of burned oil forming in one place.
In all honesty, I don't know how much of a concern it really is. But engines that were babied and suddenly subjected to high RPM (say when little Johnny inherits granny's micra when he passes his test) they often developed a sudden thirst for oil.
Curiously, a lot of manufacturers consider oil consumption of 1litre/1000miles as "within spec". I think this is unacceptable. I don't know whether the high oil consumption is due to premature ring wear or a combination of the modern preference for thin oil, thin piston rings and short piston skirts.
I don't use a litre of oil in 10,000 miles.
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I don't know whether the high oil consumption is due to premature ring wear or a combination of the modern preference for thin oil, thin piston rings and short piston skirts.
I don't use a litre of oil in 10,000 miles.
High oil consumption is almost always caused by the first owner babying the engine during the forst few hundred miles. The bores glaze and the only way to sort it is a strip and rebuild. Glazed bores always result in high oil consumption and low power.
Drive a new car normally from day one and you will never have a problem.
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I used to worry about that on my old KIA, that I got when she was 15, 4 years ago and tried to keep her below 6K, but passengers said they saw over 7K on her occasionally in fields.
Last event, passenger claimed over 8K was on the rev counter!
Think I may've worn off any lip on the bores?
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My 06 Audi A8 had done 179,000miles when the DPF became permanently bocked.
The back-pressure damaged the turbocharger.
Audi wanted £2400 for new turbo and DPF.
Local garage charged £470 to remove DPF and delete contents from it's box, fit a new turbo that I bought and supplied for ~£600. Mobile specialist reflashed ECU without DPF daemons.
£1100 repair after 180k miles is not bad on a £59,000 car as it's the only major repair.
The turbo was my fault for keeping on driving when it was losing power.
It wouldn't put me off a diesel, the driving experience is much more to my liking and not afraid of the cost of spirited driving. In a petrol, this would be an unaff***able luxury.
Why if the string f o r d within a word replaced by asterisks?
Edited by Hamsafar on 30/09/2012 at 10:54
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But I do 4,000rpm at least once a week driving hard...
And please tell me what that achives. Had diesels since 1996, never had a problem and never done that.
Never seen it written in the manual to rev the nust of a petrol or a diesel.
Its been said before by many posters, use it normally and you will be OK. Us it for 2 mile school and shop trips and you are inviting disaster.
Absolute rubbish.
I use my car for short hourneys and have for the past 6 years with no difficulties at all..
My average journey distance can be under 3 miles for weeks at a time.
Edited by madf on 02/10/2012 at 10:14
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