Changing Oil & Filter on Diesel
#21
03-09-2010, 02:50 AM
My local Mazda Dealer charged £80.00 for a oil change and a further £20.00 for reseting the computer. I never had it done as they advised it was normal for the level to rise upto halfway between full and X.
Thanks for your information.
Thanks for your information.
#22
03-15-2010, 02:01 PM
Hi Sally,
Thanks for the info. It all helps.
After my post I did some further "searching" and it appears a DPF may have both "active" and "passive" regeneration. "Active" is when the ECU deliberately adds more fuel etc to enable soot burn off whereas "passive" relies purely on temperature/gas flow to burn off the soot. I'm not sure whether the Mazda 5 uses "passive" as well as "active". As the DPF is not too far away from the engine I suspect it may use "passive" but would be happy to be corrected.
If it does use "passive" it would suggest the idea of periodically driving for 15mins at over 2000RPM would enable regeneration without so much fuel getting into the oil, thus maintaining the oil nearer normal levels.
Thanks for the info. It all helps.
After my post I did some further "searching" and it appears a DPF may have both "active" and "passive" regeneration. "Active" is when the ECU deliberately adds more fuel etc to enable soot burn off whereas "passive" relies purely on temperature/gas flow to burn off the soot. I'm not sure whether the Mazda 5 uses "passive" as well as "active". As the DPF is not too far away from the engine I suspect it may use "passive" but would be happy to be corrected.
If it does use "passive" it would suggest the idea of periodically driving for 15mins at over 2000RPM would enable regeneration without so much fuel getting into the oil, thus maintaining the oil nearer normal levels.
passive regeneration should naturally occur on Motorways. The 5 should have both.
#23
03-15-2010, 02:17 PM
I am not 100% sure if they reset the computer. The mechanic who did the oil change has worked with Mazdas for a long time and I am confident he will have done it.
Why it actually needs doing is beyond me. I have read the previous posts about possible engine damage etc and still fail to understand any link between the condition of the oil and the fuel injector timing. Also not everyones oil is going to be diluted by the same amount for the same mileage. The only thing I can think of is that some oil will be carried over into the dpf and maybe the way the ecm controls the regeneration process varies depending on the projected oil condition.
Why it actually needs doing is beyond me. I have read the previous posts about possible engine damage etc and still fail to understand any link between the condition of the oil and the fuel injector timing. Also not everyones oil is going to be diluted by the same amount for the same mileage. The only thing I can think of is that some oil will be carried over into the dpf and maybe the way the ecm controls the regeneration process varies depending on the projected oil condition.
The only possible explanation I can possibly think:
Basically Engine oil ash clogs the filter. This needs to be burnt off, i.e. inject more fuel, higher temp. More fuel dilutes the oil, has cleaning properties and basically stops the oil working at 100%. If the ecu isn't told that the oil is new, it will think that the build up should be greater and inject more fuel, which will give poorer oil, poorer lubrication etc, leading to engine damage.
That is the only theory that can explain it. Personally, I don't see that changing the oil between services, as I do will cause any harm, without resetting, but not changing the oil could quite easily. More important is to use the correct grade of oil.
from now on I will just unplug the ECU for a couple of hours when I do it. If that doesn't reset the ECU then overnight should.
The thing that gets me, is the ECU must be getting the readings wrong, if it is filling up the oil with fuel ( past the piston rings) to clean the filter, as it is obviously putting in more than required.
I for one wont be owning a high mileage one of these secondhand, thats for sure, when from experience 20-40% of my oil is diesel fuel, hate to think what that is doing to the engine!!
That and the fact that these could do with being thrashed a fair bit, doesn't bode well.
#24
03-15-2010, 03:29 PM
why fuel gets into the sump
I agree with your sentiments but not entirely your explanation concerning fuel passing into the sump and that the ECU is not working correctly.
As I understand it the active regeneration process is started by the ecu when a sensor detects a high differential pressure across the DPF. Fuel is injected during part of the exhaust cycle so that it flows uncombusted in to the DPF to burn off soot etc. Because piston rings need combustion gas to seal tightly against the cylinder, during this period they are less effective at preventing some of the neat fuel entering the sump.
Therefore the more this process can be prevented the better e.g by hard driving causing passive regeneration.
Like you I normally keep a car for 10-14 yrs and then scrap it but I am much less optomistic about this one. A shame as apart from the low profile tyres I like the car.
As I understand it the active regeneration process is started by the ecu when a sensor detects a high differential pressure across the DPF. Fuel is injected during part of the exhaust cycle so that it flows uncombusted in to the DPF to burn off soot etc. Because piston rings need combustion gas to seal tightly against the cylinder, during this period they are less effective at preventing some of the neat fuel entering the sump.
Therefore the more this process can be prevented the better e.g by hard driving causing passive regeneration.
Like you I normally keep a car for 10-14 yrs and then scrap it but I am much less optomistic about this one. A shame as apart from the low profile tyres I like the car.
#25
03-16-2010, 09:11 AM
Excessive fuel will always go past the rings, when it has not been burnt off. If it is changing the injection timing, to heat and cool, then it will have fuel being injected too early or late for combustion. There is no spark to ignite things, just pressure from the piston.
There is no way the fuel can enter the exhaust then back to the sump, it will only go one way from there. And cars don't make oil, so the only possible explanation for a rise in oil is to get fuel in it.
It is the only reasonable explanation I can see, but by all means I have little experience of DPF's first hand yet, but at the end of the day they are another box in the car, that will break, need changing then clog up our waste fill, so we can save the planet.
Can't wait really until I can find a DPF reset tool, might start offering oil changes on DPF cars as a second Job
There is no way the fuel can enter the exhaust then back to the sump, it will only go one way from there. And cars don't make oil, so the only possible explanation for a rise in oil is to get fuel in it.
It is the only reasonable explanation I can see, but by all means I have little experience of DPF's first hand yet, but at the end of the day they are another box in the car, that will break, need changing then clog up our waste fill, so we can save the planet.
Can't wait really until I can find a DPF reset tool, might start offering oil changes on DPF cars as a second Job
Last edited by coney; 03-16-2010 at 09:14 AM.
#26
03-18-2010, 10:55 AM
"at the end of the day they are another box in the car, that will break, need changing then clog up our waste fill, so we can save the planet."
AFAIK they're fitted to reduce the impact of diesel particulates on our health:
http://en.wikipedia.org/wiki/Diesel_particulate_matter
AFAIK they're fitted to reduce the impact of diesel particulates on our health:
http://en.wikipedia.org/wiki/Diesel_particulate_matter
#27
03-20-2010, 06:36 AM
"at the end of the day they are another box in the car, that will break, need changing then clog up our waste fill, so we can save the planet."
AFAIK they're fitted to reduce the impact of diesel particulates on our health:
http://en.wikipedia.org/wiki/Diesel_particulate_matter
AFAIK they're fitted to reduce the impact of diesel particulates on our health:
http://en.wikipedia.org/wiki/Diesel_particulate_matter
and then what happens to the particles?
do they magically disappear?
#29
03-13-2012, 05:52 PM
DPF - what a crock!
I have a 2009 mazda3 2.0 diesel; I have just being advised that this car has a DPF in the exhaust , and that I MUST have the computer reset at every oil change(only at Mazda dealers mind you); also if the light flashes I must take it again to a dealer; I mean ;what the hell! ; So for the life of the car its must be serviced every 10K at a dealer;*surely this is not correct.* I bought this car to do big K's economically;*
now the good bit!
The light is flashing "DPF"*so away to dealer; no I am told this DPF has "woofed its cookies"*and that will be $8000 please. yes you read it correctly, and Mazda will not do a warranty as the ECU was not reset at each oil change (that’s because I do my own services, have for 40 years)*and I did have the majors done at the dealer, at no time was I told that if this was not done I would loose warranty and amount of mediation will make them change their mind. So I put an after market on in this cost $3000.*Car is now someone else’s problem.*
so word of warning here* DO NOT BUY a car that has a single part worth*30% of the new car price...and must repeat must go to a Mazda dealer for the life of the car, else warranty is gone; and if not in warranty and the DPF dies.....I hope you have deep pockets.* i.e. save a few hundred on fuel; spend thousands and thousands on service and parts.
PS; I have owned 6 diesels in my time, and a total of 14 cars all from new; and all services by me; except for majors.* I have had warranty claims twice before with no issues... Mazda*UK/EU I am told make customers*sign disclaimers; if this isn’t a admission of a problem I don't know what is
My is now with consumer affairs and in the hands of my lawyers.
now the good bit!
The light is flashing "DPF"*so away to dealer; no I am told this DPF has "woofed its cookies"*and that will be $8000 please. yes you read it correctly, and Mazda will not do a warranty as the ECU was not reset at each oil change (that’s because I do my own services, have for 40 years)*and I did have the majors done at the dealer, at no time was I told that if this was not done I would loose warranty and amount of mediation will make them change their mind. So I put an after market on in this cost $3000.*Car is now someone else’s problem.*
so word of warning here* DO NOT BUY a car that has a single part worth*30% of the new car price...and must repeat must go to a Mazda dealer for the life of the car, else warranty is gone; and if not in warranty and the DPF dies.....I hope you have deep pockets.* i.e. save a few hundred on fuel; spend thousands and thousands on service and parts.
PS; I have owned 6 diesels in my time, and a total of 14 cars all from new; and all services by me; except for majors.* I have had warranty claims twice before with no issues... Mazda*UK/EU I am told make customers*sign disclaimers; if this isn’t a admission of a problem I don't know what is
My is now with consumer affairs and in the hands of my lawyers.
#30
03-15-2012, 04:53 AM
Totally amazed by the prices you have been quote. Most DPF repairs here are about £1000 to replace.
Mine, will get junked, and the ECU bypassed if it fails, or mayne sooner. It is already clear that it does not stop the diesel particles escaping, just chooses to dump them when it thinks the area is less built up. There is also no affect on emmision tests by removing the DPF from the car. You do however need the ECU worked on to forget the DPF system, so it will be a real shame that I will no longer be able to use a dealer to service the car.
Pity as Mazda dealers have been so good
I have still carried out 3 oil changes at 6 months from dealer servicing without issues so far. I just refuse to have oil with excessve amounts of fuel in it oing around an engine. We had to advise oil changes everytime we got a flooded car started for the simple reason that fuel is not a very good bearing lubricant.
Mine, will get junked, and the ECU bypassed if it fails, or mayne sooner. It is already clear that it does not stop the diesel particles escaping, just chooses to dump them when it thinks the area is less built up. There is also no affect on emmision tests by removing the DPF from the car. You do however need the ECU worked on to forget the DPF system, so it will be a real shame that I will no longer be able to use a dealer to service the car.
Pity as Mazda dealers have been so good
I have still carried out 3 oil changes at 6 months from dealer servicing without issues so far. I just refuse to have oil with excessve amounts of fuel in it oing around an engine. We had to advise oil changes everytime we got a flooded car started for the simple reason that fuel is not a very good bearing lubricant.