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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N57 / M57 Turbo Diesel Discussions - 335d > Understanding Diesel DPF Regeneration



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      10-16-2013, 10:37 PM   #23
Vreimann
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Dunno.

If it doesn't, it may just be on miles driven (seems to be how mine is). Would then depend on whether it goes through "heavy duty use" or not.

Oil analysis (SOA) done by many online seems to indicate diesels do well with specified oil at extended drain intervals.
Service manager I talked with says it starts with a preset number and subtracts miles driven multiplied by a factor. The factor I was told is a bunch of things that affect the oil life. Things like did the car get up to temperature, how long was the trip, average speed. So city driving miles will drop the distance to a change faster than highway miles. Not a sensor though that measures conductivity or other properties of the oil.

I wish it did measure something so the prediction of changes is more accurate.
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      10-16-2013, 11:19 PM   #24
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You'd be better off changing the fuel filter sooner than later.
My experience with VW TDI fuel filters has been just the opposite. You could actually see the dirt in the element and a substantial area still clean inside the filter when it came time to change. Dunno about the BMW filter, since I rarely found water also. I would just follow the manufacturer's guidelines unless I knew a good reason that the fuel was bad.
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      10-16-2013, 11:24 PM   #25
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Originally Posted by Vreimann View Post
Service manager I talked with says it starts with a preset number and subtracts miles driven multiplied by a factor. The factor I was told is a bunch of things that affect the oil life. Things like did the car get up to temperature, how long was the trip, average speed. So city driving miles will drop the distance to a change faster than highway miles. Not a sensor though that measures conductivity or other properties of the oil.

I wish it did measure something so the prediction of changes is more accurate.
Yeah, that sounds about right. If one is really worried, oil analysis would be a way to go. I'm not so sure that I would do this, though, given how well I take care of my cars.
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      10-19-2013, 09:29 PM   #26
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My experience with VW TDI fuel filters has been just the opposite. You could actually see the dirt in the element and a substantial area still clean inside the filter when it came time to change. Dunno about the BMW filter, since I rarely found water also. I would just follow the manufacturer's guidelines unless I knew a good reason that the fuel was bad.
Do you use the same filling station? Are you using fuel from wherever? Because fuel quality will vary which could cause your fuel filter life to vary. If you want to be anal.

When I drove from LA to Chicago some of the "diesel" was weird looking (topped off). I was in my old TDI and brought a supply of additive as placebo.
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      10-20-2013, 03:06 PM   #27
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Pierre has an active imagination with apparently, a lack of any practical knowledge or experience to back up his comments:
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One example: at the start of the talk, oil gets degraded by going down in viscosity. Later in the talk, soot makes it "thicker."
Both statements are true, and happen independently of each other for different reasons in the same oil drain cycle. The factors affecting those reasons are variable.
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Another: long drain intervals are bad if you have EGR putting "soot" into the oil through the combustion chamber. If EGR puts a lot more soot into the oil from the combustion chamber, think of all the soot combustion puts into the oil in the first place! Illogical!
Perfectly logical, if you understand the soot migration process. A well-tuned, healthy engine is designed to generate or allow minimal soot past the rings via blowby, and what is gets handled by the oil. Soot coming back through the EGR is additional to what would otherwise normally be present, cooled and more susceptible to agglomeration.
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Another was where he said that separate combustion process to clear the DPF with some designs causing oil contamination in the engine. This process is far away from the engine and has nothing to do with fuel contamination of the engine oil.
In this care Pierre, you are the one who is absolutely wrong. The injection event(s) for regeneration certainly do generate more soot later in the combustion cycle, heat the DPF and BTW, increase whatever level is traveling through blowby into the oil, through richer mixture AND HIGHER soot volume during those cycles.

Au contraire Pierre, your imagination regarding diesel soot and certain regeneration events with what's happening upstream of the DPF is clearly misinformed by an active imagination.
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      10-20-2013, 03:14 PM   #28
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Originally Posted by Vreimann View Post
Service manager I talked with says it starts with a preset number and subtracts miles driven multiplied by a factor. The factor I was told is a bunch of things that affect the oil life. Things like did the car get up to temperature, how long was the trip, average speed. So city driving miles will drop the distance to a change faster than highway miles. Not a sensor though that measures conductivity or other properties of the oil.

I wish it did measure something so the prediction of changes is more accurate.
OLM's calculating intervals like this are state of the art in our cars and do an excellent job of managing that task. If you want more detail take a sample and send it in for analysis.
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      10-20-2013, 10:50 PM   #29
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Originally Posted by Timujin View Post
Do you use the same filling station? Are you using fuel from wherever? Because fuel quality will vary which could cause your fuel filter life to vary. If you want to be anal.

When I drove from LA to Chicago some of the "diesel" was weird looking (topped off). I was in my old TDI and brought a supply of additive as placebo.
My experience was over a long period of time but limited to about 3 fuel filter changes I did myself. I'm fairly picky about getting what appears to be good fuel so obviously my experience isn't what anyone should base their own maintenance on. I just had the impression with a fairly large filter by VW that it was a safe bet to not have to change it early.
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      10-20-2013, 11:03 PM   #30
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Pierre has an active imagination with apparently, a lack of any practical knowledge or experience to back up his comments:

Both statements are true, and happen independently of each other for different reasons in the same oil drain cycle. The factors affecting those reasons are variable.

Perfectly logical, if you understand the soot migration process. A well-tuned, healthy engine is designed to generate or allow minimal soot past the rings via blowby, and what is gets handled by the oil. Soot coming back through the EGR is additional to what would otherwise normally be present, cooled and more susceptible to agglomeration.

In this care Pierre, you are the one who is absolutely wrong. The injection event(s) for regeneration certainly do generate more soot later in the combustion cycle, heat the DPF and BTW, increase whatever level is traveling through blowby into the oil, through richer mixture AND HIGHER soot volume during those cycles.

Au contraire Pierre, your imagination regarding diesel soot and certain regeneration events with what's happening upstream of the DPF is clearly misinformed by an active imagination.
I certainly misunderstood the salesman about the regeneration cycle since he mentioned the distant injector coming to GM engines in 2013 and almost immediately went into the fuel contamination issue.

But certainly the presentation had no data and what he said about EGR (and soot contamination) causing a "25-30% decrease in fuel efficiency" in diesels is a wild exaggeration. The usual quoted decrease is about 3%: see this reference:
Quote:
Though engine manufacturers have refused to release details of the effect of EGR on fuel economy, the EPA regulations of 2002 that led to the introduction of cooled EGR were associated with a 3% drop in engine efficiency, bucking a trend of a .5% a year increase.
But I guess if we let our imagination run wild, we should run to the Amsoil dealer and buy the stuff, especially since BMW's long service oil drainage intervals must be bogus and the largesse of all those that keep track of their oil analysis is also imaginary.
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