Which is more reliable - Diesel or petrol?

[bpsorrel]

Been having this discussion with a friend of mine who firmly believes petrol engines are more reliable with basically less to go wrong (swirl flaps, DPF, etc etc) and therefore can run to higher, less troublesome mileages - I believe the other way, that diesels are hardier.... Am I right or wrong? Funnily enough, we had the same discussion re: MB and BMW...... any views on that can of worms?!!!

 

[Blackman]

Here: World's Highest Mileage Car 2010 World Record set by 1966 Volvo P1800 | World Records 2011 | Book of World Records | Most Amazing Facts | Limca Records India

I think that's a petrol, no?

 

[Mactech]

But that is a mere fraction of the mileages of some diesel trucks......

 

[wemorgan]

There should be a poll on this thread

Diesel gets my vote, on the basis of technology potential. As above, trucks and ships are diesel are they not?

Back in the 80s when diesel cars were non-turbo my selection of sub-standard French cars both did 180k miles. Now owners of premium marque diesel cars pat themselves on the back when such mileage is reached.

 

[Mactech]

I suspect the question is much too broad to have a sensible answer. We need to define a few parameters.
What consitutes a service item? A block or and injector? How often are they serviced? What is reliable, anything that does not leave you by the side of the road or something that costs you no money to fix?
I can see a discussion coming on, but no real answer!

 

[Oli]

It depends on the engine, my thinking is that a big V8 petrol will manage many miles in general because it's usually not worked hard, if you're comparing like for like I've seen ex cabs like Peugeot 406 HDIs and E220 CDIs with over 300k on the clock at auctions, can't say there are many 2 litre petrol equalivelents that have done the same that I've seen anyway.

 

[Deleted member 37751]

If both are serviced and mantained to schedule, a diesel will probably do twice the mileage.

Also, petrols rev higher which will put more strain on the engine over time.

 

[Mactech]

It depends on the engine, my thinking is that a big V8 petrol will manage many miles in general because it's usually not worked hard, if you're comparing like for like I've seen ex cabs like Peugeot 406 HDIs and E220 CDIs with over 300k on the clock at auctions, can't say there are many 2 litre petrol equalivelents that have done the same that I've seen anyway.

Agreed... but is that because the wood burners cost the cabbies less in fuel bills or because they are less reliable??

 

[BTB 500]

The vast majority of piston aero engines are petrol, and reliability is extremely good

 

[Oli]

Agreed... but is that because the wood burners cost the cabbies less in fuel bills or because they are less reliable??

I'm guessing it's more likely the fuel costs, and the added reliability is obviously a bonus.
It's funny really because I remember when I was about 10 so early 90s, going in a friend of my parents car and they had to drive around to a few different petrol stations to find diesel and being annoyed that I had to spend longer in the car, at the time I didn't really know or care about what a car ran on, but it just shows how much diesel has grown in popularity now, I'm guessing it equates for over 50% of fuel sales now?.

 

[gIzzE]

I think a diesel will outlast a petrol, however with modern diesel engines there is a lot of things to go wrong and a lot of stress on them too, far more than petrol.

A diesel will probably go longer but will probably need a lot replacing.

Think of it like Triggers broom, used the same one for 22 years and in all that time it only needed 17 new heads and 14 new handles.

I would not buy a 10 year old diesel, but would happily buy a 10 year old V6 NA petrol.

As soon as diesels get to 10 years old I am out, far too much to go bang.

 

[Oli]

I think a diesel will outlast a petrol, however with modern diesel engines there is a lot of things to go wrong and a lot of stress on them too, far more than petrol.

A diesel will probably go longer but will probably need a lot replacing.

Think of it like Triggers broom, used the same one for 22 years and in all that time it only needed 17 new heads and 14 new handles.

I would not buy a 10 year old diesel, but would happily buy a 10 year old V6 NA petrol.

As soon as diesels get to 10 years old I am out, far too much to go bang.

On modern diesels I agree, but what about the older mechanical ones, like PSAs XUD engine for example?, I always thought old diesels were pretty simple even less than petrols with EFI?.

 

[Will]

I think that's the thing.

Most cars these days will develop faults during their lifetimes that make them uneconomical to repair before the actual engine wears out.

Almost all modern engines are mechanically tough in the basic sense (bores, pistons, valves, crank, bearings etc), it's the ancillaries and additional parts that cost money.

A diesel engine might well last longer, but diesel injectors, fuel pump, turbos, glow plugs etc can all cost a considerable amount to replace, and once a car reaches a certain value these items could make repairs unecomomical.

The data for what mileages certain cars have reached will be skewed anyway I reckon. If you're looking for a vehicle to do mega-miles in, chances are that you'll buy a diesel because of the economy. But in reality, a petrol engine that is properly looked after will go on for a long time too

Have seen loads of petrol engine cars with 200-300k+ that have had no mechanical engine repairs, likewise we've seen loads of diesels with general faults that cost £££s or even ££££s to repair at all sorts of mileages.

I think a better way to look at it would be the overall running costs over a vehicle's lifetime

Will

 

[BlackC55]

Petrol 100%.

 

[gina2201]

Don't know the answer...But I love my diesel mk3 golf, 150k, FSH, and going as strong as ever, excellent MPG too

Saying that, I have an E30 touring with 160k (petrol), ebay bargain has the thickest history file ever, and has flown through its past few MOT's in my ownership with no issues! No idea which one will die first, neither I hope!

 

[clever dicky]

After a nuclear war, Diesel. As it self ignites with compression.
Afraid all us petrol drivers will be walking...

 

[Will]

After a nuclear war, Diesel. As it self ignites with compression.
Afraid all us petrol drivers will be walking...

Theres's probably more electronic technology/components on a modern diesel than the average petrol car nowadays!

 

[0ptic]

Purely from a cylinder/piston point diesel has the edge. Petrol, especially if running rich, will wash the bore oil away whereas a diesel will lubricate the bores. I think this is why on older, more simple engines the diesels would go on longer. Well that and the bottom end is usually more heavy duty due to being designed for the higher compression ratio. But with the complex engines of today...probably the least of things to consider. Just look at the recent injector problems MB have had.

 

[fuzzer]

Petrol then na diesel and then a pre CDI diesel and then a CDI

 

[bpsorrel]

When I'm next in Berlin (march) I must ask one of the MB taxi drivers as I don't think I've ever seen a petrol MB taxi and I've noticed a lot of late 211s and 212s with pretty high mileages!