125TDI Improved Fuel Economy After Long Drive.

[Transporter]

The modern diesel engine has been around for more than a decade. The diesel additives that are from reputable companies didn't have to change their formulas much, if at all. I've never suggested anyone to use a snake oil additives as I only use additives that are proven. After all the Liqui Moly is the oil company and their range of additives is huge. That kind of indicate that the additives have their place in modern cars and I'm not talking just about fuel additives.

[Marakai]

Is there such a thing as a "buyer's guide"?

Which will tell you "if you drive this much, like this, with this vehicle and your engine type is such", then use XYZ, variant abc.

Maybe I've been in IT too long where this sort of thing has become commonplace and where you can pretty much punch in your numbers and out comes the recommendation (or a shortlist) that matches your parameters.

The modern diesel engine has been around for more than a decade. The diesel additives that are from reputable companies didn't have to change their formulas much, if at all. I've never suggested anyone to use a snake oil additives as I only use additives that are proven. After all the Liqui Moly is the oil company and their range of additives is huge. That kind of indicate that the additives have their place in modern cars and I'm not talking just about fuel additives.

[Amalgam]

Just on a side note, I notice that the oil temp would rise and fall during the trip.

On the trip down the ambient air temp was indicated between 39C-42C and the oil temp was 103C-108C. I put this down to the high ambient air temp. My understanding is that when the oil temp reaches 107C that a DPF regen is being done either passively or actively. Given the above and the 3.5hrs of 115km/h cruising, that the DPF would have been completely regenerated.

On the return trip home the ambient air temp was 32C and the oil temp remained around 102C. But for about 10 min it rose to 107C during normal cruise control driving on a flat piece of road before returning quickly back to 102C for the rest of the drive.

My questions is why?

[sn809]

Might sound like a dumb question but you were monitoring the temp why exactly??

EDIT: and How

[Hillbilly]

Might sound like a dumb question but you were monitoring the temp why exactly??

EDIT: and How

In the Passat you can watch the oil temp in the MFD.

Havent ever bothered but you can.

[Amalgam]

Might sound like a dumb question but you were monitoring the temp why exactly??

EDIT: and How

Because I can and because I am that sought of guy.

But mainly to see if a DPF regen was being done.

[Diesel_vert]

Yes, I'm aware of that.
...and should any emission device in any of our rides fail before 160k km is up incl. turbocharger

I don't think the turbocharger counts as an 'emissions device'. In any case, assuming the oil is fine, I don't see how any additive would lessen the chances of a turbo failure.

I will get them replaced free of charge by VW.

There are (European) penalties for any manufacturer whose vehicles don't meet European type-approval, which includes meeting Euro 3/4/5/6 emissions standard requirements by their respective cut-off dates, which in turn includes their own respective durability requirements for emissions devices.

However, I'm not so sure if these regulations are mirrored in Australian law (I don't have high hopes). Would be nice if that were the case though!

Two things are all I am going to point out

1. The standard of Diesel available in Australia is far worse than what is available in Europe, so although the tech is Euro 5 standard, the fuel is not.

2. VWW anecdotal evidence has saved me from quite a few issues and money, so I would rather believe it than what VW Australia says, also note it is just anecdotal evidence that says BP Ultimate diesel >Caltex Vorted>Shell. Most consumers will sear by BP Ultimate but there is no Ultimate diesel in a lot of the states. Also an issue is the servo you fill up from and how well they maintain their storage tanks (Diesel Algae maintenance) and weather the servo has a high diesel turn over or not (stagnant diesel). With so many variables Anecdotal is fine by me.

The Australian standard for diesel is of a Euro 5 standard (<10 ppm sulphur) and there are very little other differences between it and EN590 (European standard for diesel) so the fundamentals are fine.

I believe the issue is more downstream, where maintenance, cleanliness and upkeep practices are sometimes not all it should be.

That kind of indicate that the additives have their place in modern cars and I'm not talking just about fuel additives.

Additives certainly have their place in the modern automobile - they play an important role in engine lubricants (as blended in by the lubricant manufacturer) and also the fuels we use, both petrol & diesel (again, blended in by the fuel manufacturer). Not to mention coolants, transmission lubricants, etc.

The issue is determining which off-the-shelf additives are worth our time and money, which leads to the next quote.

Is there such a thing as a "buyer's guide"?

Which will tell you "if you drive this much, like this, with this vehicle and your engine type is such", then use XYZ, variant abc.

Maybe I've been in IT too long where this sort of thing has become commonplace and where you can pretty much punch in your numbers and out comes the recommendation (or a shortlist) that matches your parameters.

It's not that simple.

Testing in this sort of field is very expensive, time consuming and probably requires an understanding of one or several science and/or engineering disciplines if they're to be done properly.

The general public doesn't have access to laboratories, facilities, or the equipment to test their claims - much less use them. So most of time, anecdotal and manufacturer claims are all we have, but that's not to say all such claims are useless or unhelpful.

Then of course, understanding and evaluating the results is one thing - how they correlate in the real world is quite another.

Just on a side note, I notice that the oil temp would rise and fall during the trip.

On the trip down the ambient air temp was indicated between 39C-42C and the oil temp was 103C-108C. I put this down to the high ambient air temp. My understanding is that when the oil temp reaches 107C that a DPF regen is being done either passively or actively. Given the above and the 3.5hrs of 115km/h cruising, that the DPF would have been completely regenerated.

On the return trip home the ambient air temp was 32C and the oil temp remained around 102C. But for about 10 min it rose to 107C during normal cruise control driving on a flat piece of road before returning quickly back to 102C for the rest of the drive.

My questions is why?

It's normal.

In most water-cooled engines, oil temperature is dependent on load (amongst many factors).

As a generalisation, driving on the highway will increase the oil temperature (constant load/throttle) while driving in town will see temperatures decrease (intermittent load, idle periods, etc).

The DPF is another variable, but the principle still holds.

[sn809]

The Australian standard for diesel is of a Euro 5 standard (<10 ppm sulphur) and there are very little other differences between it and EN590 (European standard for diesel) so the fundamentals are fine.

I believe the issue is more downstream, where maintenance, cleanliness and upkeep practices are sometimes not all it should be.


.

Yes which is why you need to try and fill up at a servo that has a higher turn over( Dont remember if I posted that here or at WP) but at the end of the day, the consumer is getting diesel that is not the same standard as Euro, but the cars we drive are Euro spec. Ergo you need to add something. I choose to add Morey's as it works for me, you can choose not to add at the end of the day its your choice.

[Diesel_vert]

you need to try and fill up at a servo that has a higher turn over

That is good advice.

but at the end of the day, the consumer is getting diesel that is not the same standard as Euro, but the cars we drive are Euro spec.

Not that it isn't impossible for fuel contamination occur, but I wouldn't assume that the consumer is facing a situation where every storage tank in every service station on the continent is pumping out contaminated fuel.

Let me just re-emphasise that the current Australian standard for automotive diesel is equivalent to the Euro 5 standard - it's the reason why diesel engines are able to be equipped with particulate filters and be able to use low SAPS oils, otherwise the DPF would clog up real fast and the special engine oils wouldn't last as long.

I choose to add Morey's as it works for me, you can choose not to add at the end of the day its your choice.

A general piece of advice is that whatever product you use, I think it's important that it contain minimal amounts (or preferably none) of the traditional metallic additives, as they can ultimately end up as ash in the DPF.