Running in a new diesel

[brackie]

There is an increasing trend towards buying diesel cars however some of the advice that is around is dangerous to say the least. Diesel cars are new to many dealer sales staff and I've heard them giving running in advice to customers that will seriously shorten the life and adversely affect the performance of the diesel cars that they are selling. This is particularly true for the new generation of hi-tech engines with modern turbochargers. It's not the fault of the sales staff...they just don't know any better.

One of the reasons that diesel engines outlast petrol engines is that the diesel combustion process is kinder to cylinder walls that that of the petrol engine process. This means that in the early life of the engine when the rings are bedding in it's easy to glaze the cylinder walls. The worst treatment that you can give your new engine is to run it at constant high revs...for example on a freeway or on long, straight, flat country roads until the rings have had a chance to bed in. Ironically, city driving is excellent for running in an engine as it gives exactly the opposite conditions...as long as the engine and particularly the oil gets up to full working temperatures for a reasonably sustained period. Running to the shops or taking the kids to the local school and then shutting down is a killer. Diesels thrive on hard work and long periods of running.

Below is an excerpt from a post on a TDI forum overseas. I don't think I've infringed copyright here but I'm sure the author (who is a very knowledgeable poster and is an experienced trade guy) wouldn't mind. I agree with everything he says or I wouldn't quote him.

Rules that apply for the life of the car
-When the engine is cold rev the engine to at least 2,500 rpms.
-When the engine is warmed up rev the engine to no less than 3,000 rpms.
The reason for this is to keep the turbo on boost, clear the VNT guide vanes and apply firm pressure to the rings for optimal sealing against blow-by gasses. The rings need the boost to seal since it’s a turbo charged engine, babying the engine is detrimental and will lead to issues with compression if done so for very long.

First 1600km
Keep rpms below 3,800. Avoid steady rpms. Frequent firm application of power is strongly recommended up to 3,800 rpm. Avoid the use of cruise control so that you naturally fluctuate the power with your foot.

1,600-8,000 km
Use the full ~5,000 rpm power range. Avoid steady rpms. Avoid the use of cruise control. Frequent application of full throttle is recommended to help seat the rings. City driving is ideal for breaking in a TDI due to frequent stops and acceleration. Once you get to 8,000 km change the oil and perform your first service per the manual

8,000-16,000 km
Use of the cruise control is ok at this point since most of the initial break in has occurred. Continue to use occasional full throttle accelerations to continue to seat the rings. You will notice the engine become slightly louder during this phase due to less friction from the engine breaking in (normal for a diesel to become louder under lighter loads). If your going on a long drive and you are using the cruise, every so often step on the peddle to accelerate up about 30 kmph then coast back down to your preset speed.

16,000-100,000km
This is when the rest of the break in occurs. The engine from the factory will check out with about 475psi of compression pressure out of the crate. It will take at least 10,000 km to reach the peak pressure of 550psi. For the most part once you get to 16,000 km your compression will be around 510psi meaning that most of the break in has occurred.

100,000-the life of the motor
The engines I have seen so far using a 5w40 oil are maintaining 550 psi of compression pressure with over 300,000 km on the odometer. The owners have followed the advice above and do not have any oil consumption issues. This also means that with the higher pressure the engine is more efficient returning optimal fuel economy and reduced smoke output.

***Disclaimer*** Altough I agree with what is said above I take no responsibility for any detrimental consequences of following this advice. You may disagree with all or part of the above and if you do please keep this discussion going. That's what forums are for http://www.vwwatercooled.com.au/forums/images/imported/2006/06/smilegif-1.jpg

[Golf Loon]

Thats interesting reading. That would give good longevity to the life of a car. The danger surely of buying a secondhand diesel is that you dont know whether the original owner ran it in correctly.
Makes me wish I could afford a new one ;)

[SOHC]

I just learnt more;) good information thanks Brackie, however I am wondering does the motor run-in procedure also apply on gasoline engines, and do they only apply on the new technology engines? Like the TDI, FSI, or any fuel injected engines.

Cheers
Carlson

[vinderliker]

Great article Brackie, will definately taking the advice on board when i buy my Touareg(this weeks $2 lottery winnings :). I wished!!!!!!!!!!!

[brackie]

Great article Brackie, will definately taking the advice on board when i buy my Touareg(this weeks $2 lottery winnings :). I wished!!!!!!!!!!!
No, mate...both of us can't win it!

Does this procedure apply to petrol engines? Basically, "Yes". The critical parts are bedding in the rings and looking after the turbo, so if the petrol engine has rings ;) then it applies. Good compression is paramount to the performance of any diesel...especially regarding its ability to start first pop...Modern turbos (from what I have read) seem a lot more user-friendly than the old T2s etc, but they need running in too.
It seems that if you live in the city and don't do a lot of constant-speed freeway driving you'll have no trouble running in correctly.
But the thing to avoid (not just in the running in period but for the life of the car) is short runs where the engine oil doesn't get hot. It's easy to think that you've achieved full operating temperature when the water temp gauge tell you, but hot oil comes much later.

Loon.. You're dead right. Buying any used car is a gamble as you don't know if or how it was run in. And this applies especially to modern turbodiesels. I'd buy a high km country car every time if I knew it had been properly run in.

[gldgti]

i'd be willing to wager my $2 on this applying to the older idi non turbo's as well... its shorter odds too ;-)

its definately interesting stuff, and i think, unknowingly, i've driven my car well for the engine as long as i've had it.... its a very strange thing indeed, and almost counter intuitive, but i'm beginning to truely believe that diesels actually do prefer to be working hard.

an interesting little story may now be appropriate...

my mate recently sold his diesel cressida. it was a '90 with the turbo 2L-T that surfs and diesel cressidas have, and a very nice car overall.

unlike vw diesels, this engine is of the large block design, for its 2.4 litres its a large engine and being toyota, has a short rev range compared with vw engines (redlining at 4300) however i know these things are still good reliable engines. (note, the car was an auto)

my friend had the car for about 2 years, before that it was owned for about 8 years by his grandfather, out in the country - before that it lived in japan, and was imported on v'low km's. it was babied around its whole life, always driven slowly.

after my mate got it, he drove it undoubtedly harder than his grandfather, but he's not a wreckless person..so it wasnt flogged. my mate did believe in not reving it hard though...

anyway about 18months after getting the car, main bearings failed and its was dead. its whole life the car had been babied around and just done easy criusing, and i'd reckon it was certainly not run in properly.

needless to say, theres an inferiority to asian manufactured diesels (cars too ;-)) but on 220k i dont think it should have had main bearing failure.

my car is driven hard most of the time. i accellerate around town hard, as i can, its still economical, and the cars no powerhouse. i use the full rev range... i get close to the dots on the speedo often enough. to keep it economical when not driving really hard but still scooting around, i use lots of throttle through the low/middle of the rev range most of the time, and then give it WOT for hard acceleration.

with larger exhaust and non restrictive intake, my car seems happy to rev out all the time.... my oil consumption is still ok, it uses a little, but the cars on 315k and it had new rings at 260k to "fix" a blowby issue.

what do you guys reckon?

[Golf Loon]

I`m very suspicios of low kms Jap import engines. If someone has to get rid of an engine at 40,00kms, as if they look after it or change the oil. i reckon they flog em hard then ship em off to Australai.

[brackie]

These diesels are not the best. The 2.8 has an even worse reputation. At the risk of discussing Toyotas on a VW forum, they usually fail in the ring/piston/bore area.....just where poor running in usually takes it's toll. To have main bearings fail in any modern 5-bearing-crankshaft motor (except perhaps Subaru...personal experience :mad: ) is most unusual. I would suspect oil starvation. Simplistically, running in is all about seating the rings.

[coastie]

It's amazing the complete contradiction I got from VW recently. I bought a T5 multivan about 2 weeks ago and the mechanic said not to take it much over 2000 rpm for the first 1000 km. The VW logbook says not to exceed 75% of top speed for the first 1000km.

I agree with the restricted use of the cruise control for the run in period but it is so smooth to use and incredibly accurate that it is hard not to want to use it.

The advice above is certainly interesting to read but I wonder if a car manufacturer spends millions developing an engine and issue guidelines on how to run it in and then use it, why would their information be so wrong.

My personal belief is to not have constant running at a set speed but to vary it so that the cylinder does not end up with a lip created during the initial wear.

Aren't the engine bench run for a set period prior to installation into the vehicle?

I can't say that I'm driving this one any different to any other diesel I have owned. The warm up info is vital to get the car hot and to drive it immediately rather than let it idle to get warm.

I'll have to wait and see how it all turns out.

[Jettinabout]

I worked on Cape York ten years back and had a new landcruiser as a work vehicle. It was brand new and I had started to baby it a bit and had to take it in for a service. The diesel mech took me aside and had a quick and very informative chat so to speak, it went like this...

Don't baby this thing and I will show you why. See those two cruisers over there, one old and beaten up one and one six month old, clean, immaculare one. The old one has been driven by everyone on site and flogged .. we don't touch anything on it because it just doesn't ever have anything go wrong with it.

The other one is owned by one of the managers and is only ever driven by him. It is in here every other day getting fixed. The reason for that is because it is babied.

So I am telling you now to flog the crap out of that thing and you will never have anything go wrong with it....I did from then on .. he was right. Its still going strong with very few problems.;)

[Oneofthegreats]

I'm with jettinabout or along the same lines.
When I worked in dealerships for ten years, I saw cars start there life brand new & seen them evolve into either -

pristine cars - low k's & some high k's
well looked after cars - low & high
treated like sh-t - low & high
well look after & abused - low & high

I've seen absolutely mint cars with 30000k (& serviced every 6-12 month's regardless) from 94 & they run like crap!

But the standout ones were the ones that were lent out as press cars etc were they had been flogged from day one with 25km's(some requiring new tyres after 5000k's -trust me it happens. When the first M3 CSL was available to the press they were replacing tyres every time it came back!) & then done there demo k's & sold on, were the cars that rarely had any engine problems.

I've built a few high performance engines incl. V8's etc. & my daily driver 1.8 8V & I've giving it the berry's from day one & its now done 300k+. Its never let me down & it's only starting to use minute amounts of oil now.
The main thing I've learn't from building engines is you should try & keep the engine under a variably constant load for about the first 500 - 1000km.

If you baby it too much, it will clag up!

I'm with you brackie on at least driving respectfully until the engine has reached normal operating temp. which means both water & oil (especially oil) to correct temp.
That's why all of the motorsport cars have oil temp guage's

My two bob.

[Jettinabout]

I rang the local dealer yesterday to get an update on my new Jetta and during the conversation I asked the rep (who is also a mechanic) re running in the new diesels. He was very sure in his answer...."just drive it normally".

It's arriving in Perth today. Obviously made in South Africa.

[LS1 Cobra]

The Jettas are made in Mexico and the Golfs in South Africa.

If yours is here then mine can't be too far away. I better ring the dealer and find out what's happening.

Cheers

Michael

[en13]

Thanks brackie for starting this up- i've done accordingly during my first drive today!

One thing i have the habit of doing though, and i don't know if this is good/bad for the engine- I've been trying to rev it a bit- for example, using 4th gear to go at 100km/h, 3rd gear at 70km/h... but once I hit the freeway, I just let it go to 5th but then it starts to cruise- so I go to neutral... and i stay there for just a bit, then bring it down to 4th again so that the revving continues..

is this okay?
i'm what you would probably call a 'gentle' driver.. i don't particularly like to rev the engine but after all that i've read, babyying it will have its consequences so i'd rather be 'cruel' to be kind.

any help is greatly appreciated :) i sitll get a bit scared when i drive it- i feel like i'm going to choke it if i strain it too much but i just have to learn how to change my driving style... :D

[Greg Roles]

Thanks for the post brackie.

I'm new to VW forums, and to diesels as well.

I've posted around the place about run in's and championed the motomanusa concept. Certainly have had several great results from this in the past.

Thing is, thankfully, I've had the unique nature of the TDI's and the specific lube they require highlighted to me. This kind of goes against what a typical, mineral oil based, run in is all about. I'm sure that following the high combustion pressure concept highlighted in both the initial post, and in motomanusa is the best way to force rings against the cylinders and achieve a good seal, but just wondered about peoples views of doing this with synthetic oil, which kind of minimizes the effect.

I understand specific oil is required to be low ash - for the particle filter, and high shear ( synthetic ) for the cam followers in the diesel head.

Are there no oil options with the diesel??

[Greg Roles]

OK, after a few hours on the net, starting with the USA, the UK and finally back here, I am satisfied the TDI comes with an oil designed to optimise run in of the rings. Seems even dealers are confused with the oil issue, but this was the same with my outgoing car. Will have to befriend the service manager at my dealer during delivery, and see what they are using oil wise.

It appears VW recommend a semi syn for run in, and a full syn after 15000k for better long term protection. I'm happy with that!:D

[Preen59]

Thanks brackie for starting this up- i've done accordingly during my first drive today!

One thing i have the habit of doing though, and i don't know if this is good/bad for the engine- I've been trying to rev it a bit- for example, using 4th gear to go at 100km/h, 3rd gear at 70km/h... but once I hit the freeway, I just let it go to 5th but then it starts to cruise- so I go to neutral... and i stay there for just a bit, then bring it down to 4th again so that the revving continues..

is this okay?
i'm what you would probably call a 'gentle' driver.. i don't particularly like to rev the engine but after all that i've read, babyying it will have its consequences so i'd rather be 'cruel' to be kind.

any help is greatly appreciated :) i sitll get a bit scared when i drive it- i feel like i'm going to choke it if i strain it too much but i just have to learn how to change my driving style... :D

Labouring, or putting an engine under load at very low RPMs is not good for it in any situation. Labouring it causes too much of the charge to be combusted before top dead centre and this does a number of things. It increases blow-by, which can over heat your rings and they can lose their radial tension (the tension on the ring forcing it out against the bore). It is also hell on your rods and pistons, it can cause the rods to crack and the pistons to fatigue. Also, at low RPMs your oil pressure is lower, which doesn't do your bearings any good.

You don't have to beat the balls off it, just use a decent throttle percentage and rev it a bit. Up hills (unless the engine is at a comfortable RPM), you're better off to knock it back a gear or 2 and rev it to 4 grand and get the boost pumping into it than you are to chug along and labour it. Engines have rev limiters for a reason, so aslong as you are sensible, your engine will that you for sticking the throttle into it a bit and bumping it up in the RPMs now and then.

So like i said, don't bounce it off the limiter in every gear and screach the wheels at every intersection, but just lean on it, make it work a little, and it'll last for a long long time. :)

[wiking]

The recommended run in for Heavy diesels used in modern day prime
movers ( 500 hp + ) is to drive it out the dealers yard and hook
it onto a 62 ton B-Double and go straight to work.

[Buller_Scott]

you guys, this forum has been a huge source of knowledge for me (i have a polo tdi), however i have a question that alludes to a little bit of driving from column A, as well as B.

my pogo was a demo, so we can presume that it was given a decent work out during the first 5000k's of its life (after which i picked it up).

but then, i picked it up and during warm up, i would never rev it higher than 2000rpm, and once it was warm i had the (deadly, i now understand) tendency to drop it into fourth at 60km's an hour and let the engine lug at 1300rpm, because i was stupid in thinking that aslong as im within the torque range, then its all good.

since 6700k's or so, however, i have been following the guidelines as per this forum.

so my question is- given the youth of my car, is the close-to 2000k's that ive been doing that to the engine, in all reality, going to have scarred it for life/ contributed to a lower km engine life? or as long as i follow the guide in the context of how to warm up etc, will my pogo's engine still be able to lead a full life?

im in my mid twenties and i have no idea about these things (expat kid turned foreign student living in japan= never owned a car before last year), so any experience, however positive or not-so-positive, will be well recieved.

thank you.

[Pumpe-Düse]

Aren't the engine bench run for a set period prior to installation into the vehicle?

Yes they are. This is part of the reason why VW diesel and petrol vehicles do not have a 3000km "complimentary," service like say, every Ford vehicle, for example, does.

[drmvwgmad]

That seems to be true in my experience too, particularly in turbo d diesels.
I m curious about something I noticed not just on this blog, that you shouldnt idle the diesel to warm it up, but actually drive it, even under load when cold. this go s against pretty much all i ve learnt/ heard before. ??? opinions?
I've also heard that a good hard run, almost flat out, and under load, can fix glazing of the bore in a diesel.??? I definetly know that John deeres are a lot happier when worked hard.
I'm just about to buy a brand new 2.0 di golf, and not knowing anything about vw s, or there diesels in particular, am a little uneasy. I live in remote WA, so the parts availability, service costs, and reliability are a major. Is there any difference between the 2.0 litre in the 08 to the 2.0 in the 05/06?
big differences in trans, eng, or anything for that matter. Just makes me wonder if buying a second hand city diesel would be wiser over here, given the big distances/ running in scenario. Any help/ opinions would be much appreciated. Anything you can do to the 2.0 to make it go better as well?

[gerhard]

Mine is a petrol GTI, now with 1100ks. I found it quite hard to "load" the engine, since it's got so much grunt - a quick jab of the throttle off the lights and you're doing 90-100 with no effort :) I never revved it beyond 5000 in the first week, honest.....

I am assuming my rings are reasonably well sealed, though, because -

First 500ks, the engine used a bit of oil, half way between the full and add. I didn't check it on collection, so I'm assuming it was on the full mark. The fuel economy was 12l/100k using Mobil 8000 (scungy dealer didn't fill it - but I got a price I was happy with, so didn't care too much, and filled it with the Mobil)

At 500k I filled it with BP 98 and saw an immediate improvement in the fuel economy on the MFD, and the second tank returned 9.8l/100 and the oil level has not dropped any further. Seems like the BP fuel is a bit better - this second 590ks included all the very cold mornings we had in Melbourne, which always increases the consumption, so I'm happy with that.

Engine definitely feels as though it's freeing up

[mr_walker]

I've found the best way to load the TDI, and not break the speed limit *too* quickly is to get it on a good incline, drop the DSG into manual to make sure it doesn't kick down, and floor it from just over 2000rpm (but not labouring the donk). Wash, rinse, repeat.

I'm sure that whoever is behind me must think I'm a complete nutter when I do this, as I pull away and then fall back. We've got a huge hill just at the end of my trip home, just as the speed limit goes up to 100, so it works for me because the oil is also at normal operating temperature by that time.

About idling to warm up the engine - apparently it risks glazing the cylinders, and it won't warm up by idling anyway. The diesel burns very efficiently with much less energy loss through heat, so the best way to warm the engine is to start up, give it a chance for the oil to start circulating, and then drive ... but take it easy until it does warm up. Some mornings in sub zero temps my Jetta doesn't even get to full temperature by the time I'd driven the 15kms to work! Especially if the traffic was slow and I stayed under 80.

[bluey]

Found a few interesting views on running in:
Honest John on diesels (http://www.honestjohn.co.uk/faq/faq.htm?id=32)

This small engine diesel mechanic site (http://www.britishvegoil.co.uk/smallengine/vnt.html) describes how to keep your VNT turbo alive, and sounds suspiciously like the description on running in.

Norton motorcycle onwers North Texas (http://www.ntnoa.org/enginebreakin.htm) has some pretty pictures describing running in theory.

Motoman (http://www.mototuneusa.com/break_in_secrets.htm) reckons the critical time is the first 20 miles! In which case the factory run in probably does a lot of it. Has interesting photos of pistons and some good stories.

[chisler]

Hi, I brought a new Skoda RS TDI last week, it has DSG auto.

I mostly only do highway driving, would I be better off just running it in "sports mode" to get the higher RPM's?

1 thing I liked about the car so far, is I can accelerate going up hills in 6th gear, with low RPM's, is this a bad thing to do?

cheers.

[Transporter]

Hi, I brought a new Skoda RS TDI last week, it has DSG auto.

I mostly only do highway driving, would I be better off just running it in "sports mode" to get the higher RPM's?

1 thing I liked about the car so far, is I can accelerate going up hills in 6th gear, with low RPM's, is this a bad thing to do?

cheers.

Yes it is, especialy during running in period.

[Brew]

Hi just to follow up with the question above. Running in in sports mode if you mainly to freeway kms. Any views?

[gregozedobe]

I'd have thought using manual mode will give you better control over revs. You want varying engine revs, not constantly higher revs.

[benno]

What exactly is wrong with labouring the engine at low RPM? I thought diesels thrived under such treatment.

I know petrols don't, and I'm suspicious that such opinion is just an old waves tale...

[gregozedobe]

I work on the principle that if it sounds like it is doing mechanical damage it just might be (bearings, big ends, DMF etc). Plus I think I read somewhere some turbos can get a dynamic surge thing going at big loads/low revs, and I've heard it can damage impellers.

Some diesels can (and will) produce good torque at low revs, but that doesn't mean they are designed to do it or that it is good for them. What is low revs for a particular engine (eg 1,600 for a TDI) may be very high revs for a different engine (eg a 16L highway truck engine).

I don't mind low revs on a run-in TDI engine, just so long as I'm not expecting it to produce much power while at low revs (eg cruising, coasting to slow down, going downhill). If I'm expecting my 2.5 TDI to do significant work (pull a load, go up a steep hill or accelerate hard I prefer to keep my revs above 1,800 rpm so the engine can work smoothly without unnecessary stress. If I had a 1.9L or 2.0L I would probably aim for a minimum of 2,000 rpm. I apply the exact same principle to all my engines, regardless of whether they are petrol or diesel, NA or force-fed.

Diesels do thrive on hard work, but it should always be within the design envelope, not outside.

It is your engine, drive it exactly the way you want (but be prepared for the consequences of your choices).

[Greg Roles]

It's called compressor 'surge', and it's a major problem for turbo manufacture. Basically you're expecting the impeller to try and push air 'that isn't there'. The motor is runnung at low revs, there's a lower air flow, and you ask the inlet impeller ( cool side ) to boost. To my understanding, it starts to cavitate, not unlike an outboard motor that isn't in deep enough. The output oscillates, and puts tremendous stress on the turbo shaft, and it's in the surge area that impellers often shear off. Now most cars are tuned so that the potential to produce turbo destroying surge is small, but it's still possible.

Add to that the amount of soot and thus wasted diesel you're producing below the 1700 ish RPM boost range, and it's simply a good place to avoid. If I'm crusing in 6th and notice the revs drop below 2000rpm, I go up a gear. Bottom line is avoid high throttle / lagging the engine. Use the gears!!

Here's a technical explination that's far better than mine, and will give Obi Dobe a hard-on.:biggrin:

http://forums.tdiclub.com/showthread.php?p=417918

[gregozedobe]

Thanks for the link. I must admit that I have spent way, way too many hours snooping around the vast quantity of high quality info available on TDIClub. It is easy to get addicted to that forum if you are an info junkie.

[Oneofthegreats]

It's called compressor 'surge', and it's a major problem for turbo manufacture. Basically you're expecting the impeller to try and push air 'that isn't there'. The motor is runnung at low revs, there's a lower air flow, and you ask the inlet impeller ( cool side ) to boost. To my understanding, it starts to cavitate, not unlike an outboard motor that isn't in deep enough. The output oscillates, and puts tremendous stress on the turbo shaft, and it's in the surge area that impellers often shear off. Now most cars are tuned so that the potential to produce turbo destroying surge is small, but it's still possible.

Very close & nearly right on the money cogdoc

Actually compressor surge is (quoted directly from Garrett)

The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side.
Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself.
Common conditions that result in compressor surge on turbocharger gasoline engines are:
.A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body
.The outlet plumbing for the bypass valve is too small or restrictive
.The turbo is too big for the application

http://www.vwwatercooled.com.au/forums/images/imported/2009/01/tech103_enlargesgif-2.jpg

[DMS_Dan]

I work on the principle that if it sounds like it is doing mechanical damage it just might be (bearings, big ends, DMF etc). Plus I think I read somewhere some turbos can get a dynamic surge thing going at big loads/low revs, and I've heard it can damage impellers.

Some diesels can (and will) produce good torque at low revs, but that doesn't mean they are designed to do it or that it is good for them. What is low revs for a particular engine (eg 1,600 for a TDI) may be very high revs for a different engine (eg a 16L highway truck engine).

I don't mind low revs on a run-in TDI engine, just so long as I'm not expecting it to produce much power while at low revs (eg cruising, coasting to slow down, going downhill). If I'm expecting my 2.5 TDI to do significant work (pull a load, go up a steep hill or accelerate hard I prefer to keep my revs above 1,800 rpm so the engine can work smoothly without unnecessary stress. If I had a 1.9L or 2.0L I would probably aim for a minimum of 2,000 rpm. I apply the exact same principle to all my engines, regardless of whether they are petrol or diesel, NA or force-fed.

Diesels do thrive on hard work, but it should always be within the design envelope, not outside.

It is your engine, drive it exactly the way you want (but be prepared for the consequences of your choices).

It's all about peak torque though isnt it. Mine makes peak torque at 1900 RPM and due to the variable vein turbo holds it through to about 3000 RPM where it noticeably drops off