Warming up a diesel?

[en13]

thanks guys! i feel more confident now. the car has been delayed yet again but at least i'm learning new things!

[gregozedobe]

My $0.02 worth (these are just my personal opinions, and like everyone else I have no hard scientific data to back it up with, but it makes sense to me):

Drive off (gently) straight away. Excessive idling can contribute to glazed piston rings (particularly with a new VW TDI engine). The engine will get to proper operating temperature much quicker with a bit of load on it.

After a few minutes of gentle driving you can start to use a bit more accelerator pedal and revs (but not over 2,500).

When the coolant AND oil is properly warm (may take another 5 minutes after the engine coolant is up to 90C) then you can use full accelerator and rev up to 3,500 (yes, even on a brand new engine). I wouldn't do this in every gear all the time, but reasonably frequently will help your engine run in better (it increases the combustion pressure, which pushes the rings harder against the bore, which helps avoid glazing and creates a better seal/"fit").

Even if you want to drive for maximum fuel economy you should use at least 2/3rds accelerator pedal at least once or twice an hour to help prevent the variable vanes in the turbo from sticking (and besides, it's fun )

TDIs that are run in with varying revs (no cruise control allowed during the first 2,500KM) and frequent application of full accelerator tend to have better compression, run better and get better fuel economy than those that are always babied and driven very gently.

I always drive gently for the last 3-5 minutes of any journey to allow the turbo to cool down a bit before switching the engine off when I get to my destination. Similarly if I have to stop suddenly after working the engine hard (eg driving up a long, steep hill) I will allow the engine to idle for a few minutes so everything can cool off with good circulation of coolant and engine oil (generally I try to avoid idling where I can). If you switch off with a very hot turbo heat soak can cook the engine oil on the turbo shaft, leading to damage and possible turbo failure.

[en13]

thanks again gregozedobe- now i know the difference between oil and water temp! never knew there was a difference...

do you also recommend changing oil at 5000?

my friend has a toyota prado (diesel) and says that the oils are specific and special, so i shouldn't change them before the service schedule tells me to... i'm not quite sure if this is accurate- as you can tell, i don't know much about engines at all so this forum's collective brain and experience really helps!

[Mischa]

thanks again gregozedobe- now i know the difference between oil and water temp! never knew there was a difference...

do you also recommend changing oil at 5000?

my friend has a toyota prado (diesel) and says that the oils are specific and special, so i shouldn't change them before the service schedule tells me to... i'm not quite sure if this is accurate- as you can tell, i don't know much about engines at all so this forum's collective brain and experience really helps!

your friend is right, you need to use the right oil only available at dealers unfortunately. its around 80$ for 5L plus 18$ for the filter and a few bucks for the sump bolt. as long as you use the right oil and filter theres no reason not to change the oil between services its what i do.

[jets]

My $0.02 worth (these are just my personal opinions, and like everyone else I have no hard scientific data to back it up with, but it makes sense to me):

Drive off (gently) straight away. Excessive idling can contribute to glazed piston rings (particularly with a new VW TDI engine). The engine will get to proper operating temperature much quicker with a bit of load on it.

After a few minutes of gentle driving you can start to use a bit more accelerator pedal and revs (but not over 2,500).

When the coolant AND oil is properly warm (may take another 5 minutes after the engine coolant is up to 90C) then you can use full accelerator and rev up to 3,500 (yes, even on a brand new engine). I wouldn't do this in every gear all the time, but reasonably frequently will help your engine run in better (it increases the combustion pressure, which pushes the rings harder against the bore, which helps avoid glazing and creates a better seal/"fit").

Even if you want to drive for maximum fuel economy you should use at least 2/3rds accelerator pedal at least once or twice an hour to help prevent the variable vanes in the turbo from sticking (and besides, it's fun )

TDIs that are run in with varying revs (no cruise control allowed during the first 2,500KM) and frequent application of full accelerator tend to have better compression, run better and get better fuel economy than those that are always babied and driven very gently.

I always drive gently for the last 3-5 minutes of any journey to allow the turbo to cool down a bit before switching the engine off when I get to my destination. Similarly if I have to stop suddenly after working the engine hard (eg driving up a long, steep hill) I will allow the engine to idle for a few minutes so everything can cool off with good circulation of coolant and engine oil (generally I try to avoid idling where I can). If you switch off with a very hot turbo heat soak can cook the engine oil on the turbo shaft, leading to damage and possible turbo failure.

Very good comments. I would also add to cool down when driving hard & fast & pulling over for fuel [I know not very often in a diesel] The electric water pump will keep circulating coolant but as already mentioned the oil flow will stop.

[jets]

your friend is right, you need to use the right oil only available at dealers unfortunately. its around 80$ for 5L plus 18$ for the filter and a few bucks for the sump bolt. as long as you use the right oil and filter theres no reason not to change the oil between services its what i do.

I wouldn't change the oil more often than recommended unless your conditions are severe. With the new low sulpher fuels & synthetic oil be guided by VW. If you change twice as often, get on the calculater & see how your costs will blow out over your ownership period. Most original owners sell their cars before they wear them out.

[gregozedobe]

do you also recommend changing oil at 5000?

my friend has a toyota prado (diesel) and says that the oils are specific and special, so i shouldn't change them before the service schedule tells me to... i'm not quite sure if this is accurate- as you can tell, i don't know much about engines at all so this forum's collective brain and experience really helps!

Glad to help. Remember that internet opinions are like @rseholes, everyone's got one Just think about what everyone is saying and what makes sense to you before doing anything radical based on what you read. Most of the advice you read here is good.

In europe they allow VW TDIs to be set up for variable "long life" sevicing. If driven gently they can go up to 30,000Km between oil changes. I think this is a bit too long for my confidence levels. Unless you drive hard, in dusty conditions, lots of stop-start driving or mainly short trips (where the engine is frequently running at below normal temps) the Oz recommendation of 15,000Km/12 months (whichever is sooner) is best for most people.

There is a body of opinion that says you are wasting your money changing a good oil very frequently (ie every 5,000Km), and that oil actually "improves" for the first 3-4,000Km. I'm not sure of the theory, but if you want to get really overloaded with information have a look at the oils and lubrication threads on here - http://forums.tdiclub.com/

Quite a few people recommend an early "first" oil change on the basis of it getting rid of any particles of unwanted stuff left over from the engine manufacturing processes. I did my new T5 TDI at 7,500km, but my next engine will probably get changed at 1,500Km, then again at 15,000Km, 30,000Km etc. (or 12 monthly if I'm doing low mileage each year).

ONLY USE THE CORRECT SPECIFICATION OIL IN A MODERN VW ENGINE ! (and it doesn't matter whether it is a diesel or a petrol engine). Look in the owner's manual, and double check on whoever is doing the changes (and yes, even official VW dealers have been known to get it wrong).

As mentioned, the right oil can be pretty pricey, so if you need to save money I'd prefer to change at the factory intervals with the correct oil rather than use a cheaper (non-specification) oil at more frequent intervals. This (frequent oil changes) used to be a good strategy 10 or 20 years ago, but modern engines, particularly diesels, have very specific requirements and won't tolerate oils of lesser quality like older engines did).

JMHO, others may (and do) disagree.

[jets]

I have read somewhere that all the engines are test run before installation at the factory & my guess is that process would include a flush. My brother in law worked at GMH in the auto trans plant during the 70s or 80s, & every trans was test run & connected to an external oil supply & filtering system. This of course cleaned out any residual swarf etc from the previous machining processes.
This would explain why the first oil change is 15000km. With my new TDI my first oil change was at 7500km because thats all I travelled in the first year.

[en13]

alright, so by the sounds of it, i can probably get away with changing oil when the car tells me to...

i do a lot of short trips- less than 10kms so my oil change might be earlier than other's! do short trips matter if the car is run in? i'm at the running in stage so i'm trying to extend the trips if possible but i do feel a bit silly going the longest way possible to my destinations!

[jets]

When you buy a car, the car works for you not the other way round. Just drive as per normal, don't go the long way & adjust your oil change intervals to suit the conditions you are operating under.