Additive for Diesel Fuel

[RogerL]

Not sure why Mobil 1 is any better any any other oil meeting the same ACEA category - I currently use Castrol Edge FST 0W-30 ACEA-C2,C3.

Are you aware that what we call "fully synthetic" oil isn't synthetic at all? It's hydro-cracked mineral oil that behaves like synthetic oil - but the oil companies won a major legal battle to call it synthetic, except in Germany where only real synthetic oil can be called that.

Towing works any DPF hard enough to regenerate it - so no-one here should have an issue!

 

[seth1]

For the so called gains that synthetic oil produces i,d still rather stick with a good quality mineral oil.I do understand this though can lead to dpf problems.Mines never more than 30% blocked.

 

[Dustydog]

http://www.motester.co.uk/index.php?option=com_k2&view=item&id=286:mot-workshop-42-equipment-review-emissions-testing-equipment&Itemid=614&tmpl=component&print=1
According to the above link the Vosa designed test equipment is out of date.
Ok. New designs with greater accuracy are available but why should a garage shell out for new equipment if their existing is still Vosa compliant.

 

[ProfJohnL]

Hello Seth

The point I am trying to make, is its unsafe to assume that low MOT opacity results is a definitive indication of the internal cleanliness of an engine. A point Johnny agrees with. Even if you repeat the test immediately, there are so many uncontrolled variables that you are quite likely to get slightly different result. One of the variables is the actual test equipment. Compared to laboratory versions the MOT gear is not as sensitive (Coarser) and of course its calibration does allow fore some tolerance, so its not 'absolute' however for the degree of accuracy the MOT requires its perfectly acceptable and of course enforceable.

 

[RogerL]

For the so called gains that synthetic oil produces i,d still rather stick with a good quality mineral oil.I do understand this though can lead to dpf problems.Mines never more than 30% blocked.

The problem with straight mineral oil is the very short Oil Change Interval, typically 3,000 miles, but less if you're towing, because it's viscosity doesn't "stay-in-grade" nearly as well as part-synthetic or fully synthetic - a straight mineral 40 viscosity will be down to a 20 or even a 10 in a few 100 miles.

I do understand the scepticism of 20,000 mile OCIs on the specified grade so I change mine at 6,000 miles

 

[seth1]

Yes Rodger i agree but my point is take for example my equipment,the manufacture recommends fully synthetic,thats open to debate.They are on 100.000km oil drain with the recommended fully synthetic oil.On average once a year.But i can have 5 mineral oil changes (20.000km)for the price of one synthetic oil change.i still dont think engines last longer on fully synthetic,we dont have no where near the failure rate we used to have 20 years ago but thats not all down to better oils,engines are far better designed now.

 

[RogerL]

Seff - to be honest I've only run a handful of cars past 100,000 - all petrols and used fully synthetic and all ran sweeter at their disposal point than when new and had lower MoT emissions readings than the first MoT.

I don't know better than oil chemists so I take their advice and information - it's easy to get past the marketing hype, but time-consuming, by checking out the information sections in Bob's the Oil Guy website in the US http://www.bobistheoilguy.com/ and the Opie Oils website which is in the UK http://www.opieoils.co.uk/

This is why I use 0W-30 oil now, 0W-40 in my previous cars because it protects better during the warm-up phase and most wear occurs during the warm up - AFAIK only fully-synthetic can have such a wide viscosity range.

 

[JTQ]

Towing works any DPF hard enough to regenerate it - so no-one here should have an issue!

Not so sure you are right on that one; towing can at times easily push an engine into an overfuelling state where loads of free carbon get stuffed into the DPF. I am sure they get hot enough to clean but not sure that happens enough to offset the overfuelling.
To clean a DPF IMO it is best to have a longish run with the engine/vehicle as designed, ie running solo at a good steady state road speed where the engine is well over aired, rather than pushed where it is over fuelled. After all it can only be excess air that regenerates the DPF, not simply getting hot.

 

[RogerL]

Towing works any DPF hard enough to regenerate it - so no-one here should have an issue!

Not so sure you are right on that one; towing can at times easily push an engine into an overfuelling state where loads of free carbon get stuffed into the DPF. I am sure they get hot enough to clean but not sure that happens enough to offset the overfuelling.
To clean a DPF IMO it is best to have a longish run with the engine/vehicle as designed, ie running solo at a good steady state road speed where the engine is well over aired, rather than pushed where it is over fuelled. After all it can only be excess air that regenerates the DPF, not simply getting hot.

Assuming the engine hasn't been chipped and is in good condition - diesels don't over-fuel - they continually run lean (unlike a petrol) - the intake air is unthrottled and power output adjusted by altering fuel flow.

This constant lean running is the reason chipping works - it's already getting enough air so just modify for more fuel.

 

[JTQ]

Well, we will have to differ on that point; I can't have been the only person that has witnessed black smoke pouring from pre DPF diesels when working hard?
Even had it myself whilst testing them during engine development when exploring the available power envelope.

 

[RogerL]

Pre-DPF diesels do create carbon particles, aka soot, it's a natural part of the combustion process given that fuel is a hydro-carbon - as you're probably well aware DPF-equipped diesels still produce the particles but they're caught by the DPF and then then burned off by regeneration, either passively under moderately heavy use or actively by the addition of extra fuel to increase the exhaust temperature.

I feel sure that in engine development, all sorts of air:fuel ratios are tested but only acceptable ones put into production.

 

[seth1]

On older mechanical diesels that had no AFC fitted to the fuel pumps it was quite easy for them to over fuel.
Certain conditions i.e under load,slow crank speed,low fuel pressure,low charge pressure and a wide open throttle,the engine physically cannot take any air.
Modern electronic engines though?Unless the charge pressure sensor is activated either by charge pressure or a physical resistance i.e road resistance and thus a build up of pressure in the intake manifold the EDC control unit commands low speed governor/fuelling.Once charge pressure is seen the EDC then commands fuel user state,That period can sometimes produce excess fuel under load.We see it often,some late equipment does still operate with out exhaust filters.But contary to that the ideal stiochiometric AFR for a diesel is 28-32.Amazing really.

 

[Willi-Wonti]

I have noticed that I get better performance (power & mpg ) when I use the main brands of diesel than if I use supermarket diesel
I mentioned this to a tanker driver when delivering diesel to my Fire Station
He said that his company delivered to both the main brands filling stations & supermarkets which had less additives than the main branded filling stations
We have a filling station over the road from my Fire.station whose livery is red & yellow. I usually fill up on the normal diesel but every now & again I put the high performance diesel in
I was given a green badge at a TUV station in Germany allowing my car to travel into German city centers B)

 

[intransient1]

Hi All,
Interestingly fully synthetic synthetic oil do reduce the wear on your engine, as a mechanic I was also dubious.
Then I had the opportunity to open engines that had run on mineral and synthetic oils, the difference in wear was easily seen as soon as the cylinder heads were removed.
The synthetic oil engines were cleaner as the oil stops the carbon buildup, and the bores had less than a tenth of the wear after 100,000 miles.
These engines also did more mpg than the ones run on mineral oils.
So I put it in my motor and yes it is as good as that and I would not change back.

 

[JonnyG]

Umm. Given that diesel fuel itself has good lubricity or rather the additives do to lubricate the injection system and as a by product the the cylinder bores ect and given that diesel engines have alway been known for its longevity too one has to wonder why fully synthetic ie mobil one is needed. The chances are a diesel engine will last well beyond 200k with proper oil changes and bore wear will not be an issue. What will be an issue is the economical viability of replacing injector pumps and indeed injectors at 1k a job .or turbo's or Dmf's .engine wear? Not an issue with any of today's oil's

 

[seth1]

Because mineral oil damages dpf's or more to the point blocks them.so the experts say.