By on December 19, 2012

A reader tip pointed us to an issue with Mazda’s recent Skyactiv-D diesel engines in Australia. Apparently, the vehicle’s particulate filter may be the source of some engine oiling issues.

Our reader sent us this note regarding the issue

I’m really looking forward to the new skyactiv D engines coming to North America next year. As I was looking for info about them I came across issues with oil rising over the full mark. Seems to be caused by diesel leaking into the oil sump after being sprayed to burn off contaminates in the particulate filter (apparently this happens in other manufacturers diesels as well.) Most of the problems reported seem to be in Australia but apparently it is happening in Europe too. I know that the CX 5 Diesel is very popular in Japan but I didn’t find anything about the issue in Japan

Mazda sent out this leaflet to diesel owners regarding monitoring the oil, while forums have been alight with this topic. While some would-be owners have canceled their orders for CX-5 and Mazda 6 diesels, it appears that new engine software and a re-designed dipstick (which can give owners a more accurate reading of the oil level) can remedy the problem.

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59 Comments on “Mazda Diesels Facing Oil Issues In Australia...”


  • avatar
    Advance_92

    Doesn’t sound like a hard fix. Besides, other than BMW owners who can’t check their oil every now and then these days?

    • 0 avatar
      jkross22

      BOO-YAH!

      I can check the oil…. it’s just a stupid, plastic, untrustworthy stalk click away.

    • 0 avatar
      oldyak

      We BMW owners don’t check because it would get our rich
      soft hands dirty and…they don’t use much oil.
      Get off the BMW bashing already!!!!!!
      A lot of us that read this forum own BMW`s that we love to care for and….look under the hood for problems..even if its just an occasional dusting!

      • 0 avatar
        Advance_92

        Indeed, I bet every now and then some dust builds up in the corners of all that plastic cladding. But why not just have the dealer clean it when you take the car in to have its wiper blades changed?

      • 0 avatar
        Whatnext

        “..don’t use much oil at all”?? My E90 burned about a litre every two months, right off the showroom floor. I’ve never seen a modern car go through so much oil.

  • avatar
    parabellum2000

    I remember when Mazda released an update for the dip stick in the RX-8. Didn’t fix the reliability, just cut down on some complaints by customers. At least until the engine died…

  • avatar
    PrincipalDan

    As long as it works, we’re good. Glad they didn’t release it here when it was fresh and new. Although it’s odd that the Japanese aren’t having the same problem.

    • 0 avatar
      d524zoom-zoom

      Is it possible the Japanese are too proud to admit this issue?

      Just a thought.

    • 0 avatar
      CJinSD

      Do they have the same particulate controls in Japan? The same percentage of biodiesel in their fuel? Maybe the use of B20 in Australia leads to more particulates and more fuel being sprayed into the trap.

      • 0 avatar
        Numbers_Matching

        for light duty diesels (<130 kW) fuel is injected into the combustion chamber as an additional or late injection event.
        Over time there is a fuel build-up in the sump and a slight dilution of the oil. Heavy duty engines have external fuel dosing to raise exhaust temperatures prior to the DOC/DPF.

  • avatar
    Herm

    dont they use B20 diesel in Australia?

  • avatar
    George B

    Diesel pickup trucks, at least the modified high-performance ones, don’t appear to have particulate filters. Is this a case of different US EPA regulations for larger trucks or do the owners remove the pollution equipment? No particulate filter = no need for the fuel wasting engine damaging run-rich operation.

    Black Cloud Diesel Performance http://www.blackclouddiesel.com/

    • 0 avatar
      RobertRyan

      They would be Illegal in Australia without the filters.

    • 0 avatar
      Numbers_Matching

      All diesel pick-ups have some form aftertreatment system installed from the factory as per EPA on highway guidelines. Almost all diesel pick-ups are now using DOC/DPF/SCR based systems. Some are getting away with just the DOC/DPF and exploiting thier EGR further – with some consequences over long term reliability.
      There are ways of deleting/disabling these systems — of course.

    • 0 avatar
      danio3834

      Removing the DPF and DOC is usually the first modification a modern diesel owner performs. They only hamper performance of the engine and in the case of regeneration for the DPF, can eventually cause engine damage if left unchecked.

      • 0 avatar
        jmo

        They how do they prevent spewing carcinogenic particles into the environment?

      • 0 avatar
        LeadHead

        By usually, you mean only by the select few enthusiast diesel owners. Probably several thousand, perhaps into the tens of thousands at the most remove the DPF and other emissions equipment

        The vast, vast majority of modern diesel vehicles remain completely stock.

    • 0 avatar
      Wheatridger

      You mean like the clown in my neighborhood who’s added a straight vertical exhaust pipe, steamboat-style, in his empty pickup bed? He seems to enjoy gunning it to spew a black cloud in his wake. Reminds me of a squid squirting ink, or a lingering problem with his toilet training. This kind of bozo proves to me that fuel is still too cheap, and that macho aggression takes an endless number of forms. Meanwhile, my little two-liter TDI must play by a tougher set of rules.

  • avatar

    Some more detailed information on this problem, which appears to affect many DPF cars:

    http://www.stocksy.co.uk/articles/Cars/diesel_particulate_filters_dpfs_and_rising_oil_levels_the_uk_government_demonstrates_the_law_of_unintended_consequences/

    • 0 avatar
      CJinSD

      It does seem that biodiesel is a big factor, and that the government knew it when they regulated B20 into use. Nice.

      • 0 avatar
        colin42

        I’m not seeing any logic in the blog above that places the blame with bio diesel. The issue i expect is late injection of diesel for dpf regen that is impacting the liner wall and washing into the oil sump. The issue is not just increasing oil level but dilution of the oil and cylinder liner wear from the wall washing. By diluting the oil with diesel the viscosity will be reduced and won’t provide the protection of the engine critical components.

  • avatar
    cRacK hEaD aLLeY

    Syphon the excess back into the fuel tank for extra savings.

  • avatar
    gslippy

    Sounds like a minor issue. I love software fixes.

  • avatar
    danio3834

    Welcome to the wonderful world of emissions strangled diesels.

    Crankcase oil growth has been an issue on all diesels, especially in the light truck market with the advent of particulate filters and the regeneration process used to clean it.

    As described in earlier posts, fuel is injected down the exhaust to burn out the soot in the DPF. Not only does this kill fuel mileage, but it washes down the cylinder walls and causes oil growth in the crank case.

    This is particularly an issue in forced induction diesel engines because pressure in the crank case will cause oil accumulation in the intake system and charge air cooler.

    Because it’s a diesel, and is compression fired, the oil becomes an uncontrolled fuel source. Once in the intake system, it causes the engine to run away until it self destructs. Or in in the case of some engines, consistently overfuel certain cylinders until they melt. In a diesel, rich is mean.

    This has caused many engine failures in light trucks since it’s introduction, and you have your friendly neighborhood regulators to thank for it.

    • 0 avatar
      jpolicke

      How does fuel injected into the exhaust stream end up on the cylinder walls or the crankcase? My TDI Jetta had other issues but this wasn’t one of them.

      • 0 avatar
        danio3834

        The extra fuel used for regeneration is pulsed from the in-cylinder injectors during the exhaust stroke which then travels down the exhaust into the catalyst.

        Some inevitably washes down the cylinder walls over time and creates oil growth.

        Your Jetta may not be equipped with a DPF.

      • 0 avatar
        redmondjp

        On some earlier diesels (such as my 1996 Passat TDI), they actually had a supplemental fuel injector on the exhaust pipe pre-catalyst, but I believe that it was theoretically there to get the catalyst up to temperature quicker. It didn’t work, and VW had to modify the ECM software to deactivate it (lots of extra-smoky cold starts!).

    • 0 avatar
      mr_min

      To add to Danio’s post, the other issue is that Modern Gasoline and Diesel engines take longer to warm up, to enable them keep cold start emission regulation.
      This in turn means that when the vehicle is constantly driven short trip 2 items happen.
      1. Increased wall washing due to richer mixture from cold start.
      2. A higher rate of DPF purging required because of soot build up.
      -> Engine oil does not get hot enough to boil off the excess fuel in the engine oil, leading to increasing oil level.
      A software fix is not going to solve this…
      The worst part is that your engine oil turns into something which looks like oil but has low lubricity, so the next time you have a high load eg Towing etc. You can end up spinning a big end bearing.

      • 0 avatar
        LeadHead

        Incorrect, modern engines are designed to warm up as QUICKLY as possible. The faster they warm up and enter closed-loop operation – the happier the EPA is.

      • 0 avatar
        jpolicke

        Danio, my ’09 TDI was most definitely equipped with a DPF. I know because it’s incorporated with the number 1 cat and was cited as the reason my dealer quoted me $6000 to have it replaced after I threw a CEL. Although it was covered by the emissions warranty (car had 74,600 mi) I immediately traded the car in. This, following the turbo failure at 66000 mi, convinced me that this was a money pit waiting to open.

      • 0 avatar
        mr_min

        LeadHead, I’m refering to the shift between Euro2 and Euro4 for the emission cycle. Your statement is partial correct. Yes they are designed to warm up quickly, but this competes with the need to not run too rich during the warm up cycle.
        The earlier emission cycle had a warm up period which was not counted in the total emissions. Now the emission cycle includes the start up/warm up emissions as well. In the earlier days of Cat’s, car companies use to run very rich to heat up the cat quickly.
        Many of the Euro4-6 Diesel cars I have driven take at least 10km to warm up if you drive gentle. I have noticed the same trend of gasoline/petrol cars.

  • avatar
    drewtam

    The DPF or Diesel Particulate Filter is an emissions filter in the exhaust system. This device traps soot and PM emissions (black smoke). These trace emissions are a mixture of pure carbons and poly-aromatic hydrocarbons. The smallest of these particles (e.g. PM2.5) are found in studies to be carcinogenic.

    The DPF can only hold so much soot before it is full and begins to restrict the exhaust flow. The soot must be oxidized into harmless CO2 and H2O which passes easily out of the filter, clearing it to trap more soot. The oxidation process can be caused by simply getting the exhaust air hot enough. Diesels run lean, so there is excess oxygen readily available in the exhaust stream, it just needs to be activated by heat.

    This heat can be caused by running the engine very hard. It just needs to be run long enough to completely oxidize the soot. This is highly unusual for automotive applications; it is very rare to give a passenger vehicle 50-100% throttle for 10-30mins at a time (salt flats?). Since the oxidation is a byproduct of running the engine hard and is not controlled by the computer, this is called “passive regeneration”.

    Alternatively, a small amount of diesel fuel can be injected into the exhaust and reacts/burns on the DOC catalyst ahead of the DPF. This reaction of raw fuel heats up the exhaust enough to induce the soot to oxidize in the DPF. Since the exhaust temperature is actively heated by the engine computer controls, this is called “active regeneration”. This style of active regen with raw fuel injection into the exhaust is called “dosing”. There are other designs to achieve this heating. These active regens can last for about 10-60mins depending on the design and soot load.

    If the Mazda dosing system is in-cylinder fuel injection during the exhaust stroke, then they may have control calibration issue causing the fuel to drip past the piston rings into the crankcase, thus diluting the oil with fuel.
    Or it may be caused by the operator consistently turning the motor off during a regen event. I am not familiar enough with the symptom details to know for sure. Besides, I already got a day job which I need to get back to…

  • avatar
    cRacK hEaD aLLeY

    makes one wonder what the owner of this diesel would do if he had to send it to the dealer for a tune up every 20 hours or so of use http://youtu.be/kUurXdTPgfg

  • avatar
    rnc

    And once again the conspiracy to keep CNG out of the automotive sector continues. Not only could it be used in place of that new lovely refrigerant, but standard diesel engines can run on a mix of 20% diesel/80% CNG, with some mods you can increase the CNG % to 90%, significantly reducing the need exhaust treatments, best part is to make it work they have to kick up the compression ratio, more power for same amount of fuel usage, without urea.

  • avatar
    APaGttH

    Well of course they have engine oiling problems. The poor cars are upside down being in Australia so all the fluids are running to the top end of the engine.

    Sheeze.

    ;-)

  • avatar
    TonyJZX

    i feel a bit of schadenfreude about this… why do you need diesel?

    its a lot more expensive at purchase time, more expensive to service, the utility of diesel isnt all that apparent over gasoline in this vehicle, sure you use a little less fuel but the stuff is a lot more expensive… now this is not a landcruiser but rather an urban CUV

    the new 2.5 gasoline skyactive even in 2wd would probably be enough

    • 0 avatar
      Brian P

      Depending on local fuel prices – DO remember that what you see in your local area is not the way it is everywhere else! – the additional purchase price could be recovered in a couple years of driving, and after that, you are home free. Servicing? Well, I actually own a diesel VW, so maybe I know something about this. Mine has needed no more maintenance than any other car. Sure, you have to use a certain rather expensive engine oil, but you only need to change it half as often, so in the long run, it’s the same money and less aggravation. Air filter? Same as an ordinary car. Fuel filter? Yeah, you have to change that every 32,000 km. It costs about $20 and swapping it out is an easy DIY 5 minute job. But on balance … no spark plugs.

      I have 409,000 km on mine and it’s still running well. It has earned its keep and repaid the extra initial purchase cost several times over.

      In my area, diesel fuel is NOT “a lot more expensive”. On a yearly average, it’s the same as gasoline within a few percent. But the car uses 40% less of the stuff.

      • 0 avatar
        TonyJZX

        silly me to assume that if there’s an Australia in the title, one might assume that the discussion would go along the lines of Australia

        as i said, i have no issue with diesel if it suits the task, if you’re towing or carry heavy loads or even in Range Rover or Audi Q7 type SUV… but in a 3,200lb urban SUV? that has the offroad ability of a Porsche Cayenne and the same probability of being used as such?

      • 0 avatar
        Luke42

        Torque and MPG.

        I used to own a Jetta TDI. Great engine, fun to drive, but a terrible car overall. The 96hp engine in it has as much torque as the 190hp V6 in my old Escape, so it was very nice to drive. And I had to drive really aggressively to get it under 42MPG.

        I’m not going to own a Volkswagen again, but I’d love to own a diesel passenger vehicle again.

  • avatar
    el scotto

    Uh, isn’t this an engineering fail? Imagine the snarkfest if this engine was made by GM or Ford.

    • 0 avatar
      redmondjp

      Um, it’s there if you look for it. Take a look at the Ford Truck forums and the issues they have had with the 6.0 and 6.4 diesels. Oh, and yeah, you’ve gotta pull the truck cab off of the frame to work on one too . . .

      Not to mention the Youtube videos of the early-DPF-equipped Ford diesel trucks idling at streetside when the regen cycle starts – watch out and don’t stand near that flamethrower, er, um, I mean the tailpipe!

      And the Cummins diesels have their own issues – my favorite is the under-valve-cover fuel lines leaking diesel into the engine oil, until the engine bearings are shot. They don’t put an overfill warning float switch on the crankcase!

  • avatar
    niky

    Biodiesel contamination of crankcase oil has always been a problem with automotive diesels, and DPF cleaning utilizing the regular injectors is basically a contraindication for using B100. A lot of biodiesel users have these issues with everything from VWs to BMWs.

    This could be cured easily by using an extra injector in the exhaust, instead, but vanishingly few makers do this.

    • 0 avatar
      redmondjp

      Because that would cost another $20 . . . it’s a sad day when the beancounters trump good engineering, but very few companies make engineering-based decisions these days.

      • 0 avatar
        golden2husky

        Agreed. It seems the simple answer is to not inject extra fuel into the engine where it can cause problems, but to inject it into the exhaust where any extra heat issues are far more easily settled. Cheapness over sound design. Of course, the rednecks that like choking those behind them in black filth can far more easily disable the external system, so there is a good case for a direct injection type of system.

      • 0 avatar
        PrincipalDan

        @golden2husky, absolutely I am a diesel supporter and want to see Mazda do well with this engine. I would seriously consider a diesel 6 or a diesel CX5 (especially AWD) but everytime I see one of those douchebags in a diesel truck with huge stacks spewing black smoke I think… “You’re the reason regular people want nothing to do with diesel.” (Chrome stacks are fine, I put dual pipes on my truck for a reson but for the love of god I shouldn’t have to drive through a cloud of black smoke just because I’m behind you and you decide to step on it.)

  • avatar
    DenverMike

    I remember when diesels were way simpler than those darn carbureted and cutting edge, computer/fuel injected gas engines. I had no idea how to set points or what the heck a carburetor bowl was, but I could figure out and repair any diesel drivability problem back in high school.

    Even then, it was tough to break a diesel, no matter how hard you beat on it and ignored maintenance. I knew when it was time to change the fuel filter when it wouldn’t drive over 45 mph.

    Diesels had all the advantages, and you’d be crazy not to get one if it was an optional engine.

    Damn, how the tables have turned!

    • 0 avatar
      rnc

      The amazing diesels of the 60′s and 70′s were so amazing because they weren’t quite sure what was happening in the combustion chamber so they were overbuilt like the a 1920′s bridge (as soon as they got mainframes and simulation programs working), they started making them for the function required (now the rest didn’t pull a GM and just take a gas engine, add glow plugs, increase compression and hope for the best, that was making an engine to the bare bones minimum required), my Dad’s 81′ caddy was such a piece of crap that the dealer basically took it back and gave him an 83′ olds 98 deisel, the car never really had any problems with the engine (but it was his last GM product), when we lived in Mass. during the winter it had to be plugged in over night. (I was amazed by and loved those 20 or so idiot lights that had to go off (ding, ding, ding) before cranking thinking they were some sort of state of the art nasa tech, when in reality it was just giving time for the plugs to get the Cyl. to temp for initial compression ignition)

  • avatar
    jal142

    An engine with a perpetually rising oil level? Maybe they can add this technology to the 2017 RX-7.

    When life gives you lemons….

  • avatar
    indi500fan

    When we got some of the pre production 2007 spec truck engines in our lab to run back in the 2006 time frame, I said to myself: these babies aren’t going to age well. It looks like that’s the case bigtime. Any light duty diesel vehicle that isn’t covered by some type of extended warranty is probably going to be an economic loser (vs equivalent gasser) over the long term just due to repair costs.

    Throw in the decreasing gap in fuel economy due to DI gassers getting better and USEPA diesels getting worse, and the govt has achieved its goal of keeping ld diesels off the market.

  • avatar
    michaelfrankie

    As the old saying goes: A lot of things have to go right to make a gas engine run and a lot of things have to go wrong to make a diesel not run.

    Not so much anymore.


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