Diesel engines - run them every day?

zbluebirdz

Was talking to a friend's wife about her new car. Initially, she was going to get the diesel model, but was told it would better to get the petrol model. I asked her what made her change her mind. Apparently a couple of salesmen said cars with diesel engines needed to be run/used every day. But she only uses the car 1-2 times a week ...

Is this correct? - Diesel engines needs to be run/used every day? If so, why? What would happened if you didn't?

CiniO

zbluebirdz wrote: »

Was talking to a friend's wife about her new car. Initially, she was going to get the diesel model, but was told it would better to get the petrol model. I asked her what made her change her mind. Apparently a couple of salesmen said cars with diesel engines needed to be run/used every day. But she only uses the car 1-2 times a week ...

Is this correct? - Diesel engines needs to be run/used every day? If so, why? What would happened if you didn't?

Yep.. That's true.
And also all diesel owners must make sure they are started before 9am everyday, as otherwise they won't last long.

challengemaster

They don't need to be run every day, in fact mine is sitting up 5/7 days a week. What they do need, particularly new diesels, is long drives and high milage.

101sean

Majority of diesels have Diesel Particulate Filters (DPFs), lots of short runs and little use wrecks them expensively. See the dozens of posts on them clogging up.

bazz26

Before the days of cheaper motor tax, diesel cars were actually bought for their entended purpose - to be driven. These days they are bought by people who have no actual use for them but are drawn by cheaper tax and a few cent saved at the pump which is debatable if not doing alot of driving.

Diesel engines are agricultural by design but in order for them to perform similarly to petrol engines and make then cleaner to pass strict emmission regulations, manufacturers have put the likes of dual mass flywheels (DMF) on them to reduce vibrations and clatter, they also fitted diesel particle filters (DPF) to burn off the soot they generate.

Short trips in diesel cars can cause all sorts of problems over a sustained period of time such as the blocking of the DPF as the engine needs to operate at a sustained temperature for a certain length of time in order for the DPF to perform it's function. Otherwise it gets totally blocked and will need to be replaced at a cost of €1000 upwards which totally cancels any savings any low mileage driver would save at the pump on fuel. DMFs have been known to prematurely fail also, again another expensive repair.

dr.fuzzenstein

bazz26 wrote: »

Diesel engines are agricultural by design but in order for them to perform similarly to petrol engines and make then cleaner to pass strict emmission regulations, manufacturers have put the likes of dual mass flywheels (DMF) on them to reduce vibrations and clatter, they also fitted diesel particle filters (DPF) to burn off the soot they generate.

Well, my CMax is laid up for some work on it at the moment and I'm driving an '02 1.4 Petrol Polo in the meantime.
Oh for the joys of that crisp, responsive engine?
It's a dog compared to the diesel Ford, it runs out of puff over 4k rpm, power (well, for lack of a better word) is available between 2-4k rpm, at idle doesn't sound far off to a diesel, but at least it's not smelly?
It stinks like a fuel depot.
Granted it's not new, but where am I going to get money for a new car?
Just to put the stereotype right:
A good diesel (even a slightly clattery one like the old 1.8 TDCI Duratorq in my Ford) can be every bit as nice on the move. And faster. And more powerful.
Sure, if your engine is DOHC, 16 valve, variable valve timing, revs to 7k, has electronic ignition and multipoint injection, it will be nice.
But your average run off the mill petrol with pushrods, wheezy injection and in fact wheezy everything is a dog, always has been, always will.
I have driven enough n/a petrols to know that the ones that reward you with fuel efficiency are clattery old ratbags, the ones that drive nice will make you poor at the pump and the ones that drive nice and do 40+mpg are new and will cost a fortune.
Power, fuel efficiency and cheap.
For a petrol pick two, but only two.
Maybe also for a diesel, but I've driven loads of them and I'd have a clattery diesel over a ratbag petrol any day.

Also, modern diesels have their problems, but with 1 liter petrols coming up that deliver 120 hp with whirligigs and gizmos, don't think they're not going to break down by the shedload.

knifey_spoonie

Didn't think we were back in the 70's, pushrods ffs don't think you are comparing like with like.

I would say you can't name one car that has been released here in the last 15 years that has had a pushrod engine.

Electric ignition has been pretty much standard for the last 15 years.

dr.fuzzenstein

knifey_spoonie wrote: »

Didn't think we were back in the 70's, pushrods ffs don't think you are comparing like with like.

I would say you can't name one car that has been released here in the last 15 years that has had a pushrod engine.

Electric ignition has been pretty much standard for the last 15 years.

OK, maybe not pushrod.
But a run off the mill 1.4 n/a petrol is hardly going to set anyone's hair on fire.
I've driven enough Focuses, Fiats, VW's with small petrol engines to say they're not exactly scintillating.
Of course one could go for a 1.8 or above, but for a daily commute of nearly an hour you'd better have deep pockets.
Normally I drive a diesel Focus and I love it for commuting, you get the bigger engine with fewer of the fuel penalties.
It works for me due to the mileage I'm doing, if I was pottering into town, a small petrol would do.
I don't see any petrol engined car the size of the CMax that is nice to drive, has some power and will do 50 mpg.

They won't do 50mpg but they won't be laid up for major work either
On long spins loads of nice to drive petrol cars will return 35 mpg easily, will have been cheaper to buy than the diesel c max and would be less likely to give trouble.

bazz26

That 1.4 litre VW engine is probably the worst example you could have used, they were a dog of an engine.

Tigger

knifey_spoonie wrote: »

Didn't think we were back in the 70's, pushrods ffs don't think you are comparing like with like.

I would say you can't name one car that has been released here in the last 15 years that has had a pushrod engine.

Electric ignition has been pretty much standard for the last 15 years.

Ford ka had a Kent in it till 2002

dr.fuzzenstein

RoverJames wrote: »

They won't do 50mpg but they won't be laid up for major work either
On long spins loads of nice to drive petrol cars will return 35 mpg easily, will have been cheaper to buy than the diesel c max and would be less likely to give trouble.

Well I couldn't afford 35 mpg.
Also, the CMax has done 100k km over two years without giving a lot of trouble, so that's not too bad in my book.

dr.fuzzenstein

bazz26 wrote: »

That 1.4 litre VW engine is probably the worst example you could have used, they were a dog of an engine.

Tell me about it!:(

keithclancy

zbluebirdz wrote: »

Was talking to a friend's wife about her new car. Initially, she was going to get the diesel model, but was told it would better to get the petrol model. I asked her what made her change her mind. Apparently a couple of salesmen said cars with diesel engines needed to be run/used every day. But she only uses the car 1-2 times a week ...

Is this correct? - Diesel engines needs to be run/used every day? If so, why? What would happened if you didn't?

Its to do with distance more than frequency. Diesels are good for long distance and bad for short trips.

I'd say you should run any car every couple of weeks at least to keep the battery charged up.

Del2005

dr.fuzzenstein wrote: »

Well I couldn't afford 35 mpg.
Also, the CMax has done 100k km over two years without giving a lot of trouble, so that's not too bad in my book.

The OP is not asking about what car to get for long runs, where diesel win hands down, but about cars for short irregular runs where petrol(or hybrid) wins.

Tea 1000

dr.fuzzenstein wrote: »

Also, modern diesels have their problems, but with 1 liter petrols coming up that deliver 120 hp with whirligigs and gizmos, don't think they're not going to break down by the shedload.

About 20 years ago didn't Suzuki have a 1 litre GTi Swift with 100bhp with no turbo? So 20 years later getting 20 more bhp by adding a turbo shouldn't be too much like black magic. They've been turbo charging petrols before diesels. It's only about 15 years ago since the majority of diesels just moved to turbo, before that the likes of Carina E's had 2 litre diesels with around 68bhp, now everyone expects 3 times that!

Tea 1000

Tea 1000 wrote: »

About 20 years ago didn't Suzuki have a 1 litre GTi Swift with 100bhp with no turbo? .........

No, swift GTi was a 1.3.

There was a 1l turbo Charade GTi alright I think.

dgt

Short trips you say? I use a 1.9TD as a daily driver to do.... Approx 16 miles for 4 days a week. 4 trips of 4 miles. From Sat to Monday its very different (often racking up over 250 miles on the weekend alone) but for most of the week its lovely short trips to the town and back.

I see no problems with short trips when the car is properly being looked after. Which in a lot of cases of DPF and DMF trouble is down to improper use/negligence...

It does help I have neither of those mind you :pac:

Bpmull

A diesel doesn't have to be driven everyday. My diesel sits up 4 days a week when I'm in college and I've no hastle I got a new battery and it starts first touch of the key. Diesels can be driven short distances but it's not good for the dpf but that's it it's for no other reason diesels can't have short trips. Also the risk of dpf failure is dramatically decreased if a car is service regularly with correct oil. Wrong oil means more soot and build up. Also the problem with most diesel drivers Is they are so upsessed with consumption and never drive the car over 2k rpm. Diesel need to be well driven up through the gears this heats the dpf and helps it. So many people change at under 2k rpm every time and frankly it's not good for the dpf. Obviously drive it easy when it's cold.

Nissan doctor

Short trips on any engine is not ideal but the deposits produced by diesels will quickly effect the cylinder chambers themselves, injector nozzles, EGR valves, DPF's etc etc.

Also, diesel engines not being run at optimal temperatures for long periods causes bacteria and other sludge build up in the fuel tank and fuel system itself due to our current low sulphur diesel.

@OP, it appears that the salesman was giving correct advice for once, at least regarding diesels not being suitable for constant short trips(although they don't need to be started every day, in fact, just starting it a running it for a few mins every day would actually be worse then not using it for a few days)

CiniO

RoverJames wrote: »

They won't do 50mpg but they won't be laid up for major work either
On long spins loads of nice to drive petrol cars will return 35 mpg easily, will have been cheaper to buy than the diesel c max and would be less likely to give trouble.

I took my mazda 6 for a spin to Dublin and back last week (nearly 600km) and I decided I'll try to drive as economical as I could.
I came down to average fuel consumption of 6.7 l/100km (about 42MPG).
So it's not much worse than average diesel of that size.
But unfortunately I wouldn't have enough patience to drive like this for everyday. Normally my mazda consumes around 8.5 l/100km (33MPG).

PaulKK

CiniO wrote: »

I took my mazda 6 for a spin to Dublin and back last week (nearly 600km) and I decided I'll try to drive as economical as I could.
I came down to average fuel consumption of 6.7 l/100km (about 42MPG).
So it's not much worse than average diesel of that size.
But unfortunately I wouldn't have enough patience to drive like this for everyday. Normally my mazda consumes around 8.5 l/100km (33MPG).

If you drove a diesel as economically as you could you'd get a lot more too.

I got 58mpg out of my old Passat before, normally got 48mpg.

zbluebirdz

Thanks for the interesting responses/comments.

Basically, it boils down to diesel engines preferring to run cross-country marathons, not 100m sprints. I'll bear that in mind when I take my "tractor" out for it's weekly run ...