Diesel in Engine Oil

Faults and Technical chat for the Mazda CX-3
Mcgrimes
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Diesel in Engine Oil

Post by Mcgrimes » Wed Jan 17, 2018 10:02 pm

Gents

I purchased a 15 plate CX3 about 6 months ago and the spanner began to come on intermittently a long time before its next service is due.

Having taken it in to the dealer, it was found the oil level was at ‘x’ and there fore replaced with all 4 injectors replaced due to working incorrectly ; seems others have had this problem also where diesel finds its way into the engine oil.

Is it likely to happen again? If so will it be covered under warranty next time?


1Monty
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Location: Essex

Re: Diesel in Engine Oil

Post by 1Monty » Thu Jan 18, 2018 7:52 am

I couldn't say if it will happen again, only time can tell. I would like to think if it did within the warranty period then it would be covered. But as and if it does, that is then down to your dealer or Mazda UK.
SINCE FEB 2018 I NO LONGER OWN VEHICLE
CX-3 Sport Nav - 2.0L Petrol - 2017 - Manual - 2WD - Eternal Blue Metallic - Half Leather - 44.3mpg on a good day down hill with a strong wind behind 😎


DaveG
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Re: Diesel in Engine Oil

Post by DaveG » Thu Jan 18, 2018 1:13 pm

Diesel in engine oil causing the oil level to rise. I am sure that is to do with a partial regeneration re the DPF. Might be wrong.

I am sure anchorman will give you a very good analysis in due course.
CX3 Sport Nav - Petrol - Auto - safety pack - snowflake white - 2019


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anchorman
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Re: Diesel in Engine Oil

Post by anchorman » Thu Jan 18, 2018 7:42 pm

Hmm well, you’d better get used to it.

I don’t know why the dealer changed the injectors unless it was running badly because it will ordinarily dilute the oil - that’s why the X is there.

So what’s happening? As indicated by Dave above, the vehicle will regenerate (purge out all of the soot caught in the filter) by super heating the exhaust. It does this by injecting neat fuel through the cylinders on the exhaust stroke. It’s a bit like an afterburner on a fighter jet and it literally has pure blue fire inside the exhaust. It stinks of burning. The clues it is regenerating are that the istop doesn’t work, it makes a booming noise on overrun and if you park up before it is finished, the fans will keep running on the engine.

The problem is that so much fuel is sprayed into the cylinders that some of it gets past the piston rings and into the sump. The oil will creep up the dipstick and all you can do is dip it regularly (maybe every couple of weeks) to just get a feel for how quick it fills up. Longer trips are less likely to cause problems than shorter trips because the regeneration will be completed without the chance of diesel pooling on the pistons.

As you’ve seen, the car will tell you if it senses low viscosity but just in case it doesn’t, keep an eye on that oil. It might settle down now you’ve got it. Just an aside, the oil data MUST be reset immediately following an oil change or it will start comparing old oil with its programmed viscosity and throw up a problem prematurely.

It sounds bad all this but it isn’t necessarily. It’s just a case of getting used to it and it is very common on modern diesels.
CX-5 Sportnav diesel auto. AWD


DaveG
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Re: Diesel in Engine Oil

Post by DaveG » Fri Jan 19, 2018 12:18 pm

When I ran diesel cars in recent years and they introduced the DPF, Every couple of weeks I used to take them down the dual carriage way/motorway and give them a Italian tune up. I kept it in third or fourth to keep the revs above 3000 for about thirty minuets.

This may seem a waste of fuel etc but most of my driving was stop start, and it helps prevent issues with the DPF , if the warning message comes on warning of a partially blocked filter that is what you will have to do anyway to force a Regen.

Worth bearing in mind if most of your journeys are short.
CX3 Sport Nav - Petrol - Auto - safety pack - snowflake white - 2019


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anchorman
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Re: Diesel in Engine Oil

Post by anchorman » Fri Jan 19, 2018 1:21 pm

You can actually force a regen on a CX-3 without turning a wheel. It will run through a variety of engine speeds for set periods of time all on its own.
CX-5 Sportnav diesel auto. AWD


DaveG
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Re: Diesel in Engine Oil

Post by DaveG » Fri Jan 19, 2018 2:17 pm

Anchorman that is interesting not sure how it works, if you have time can you explain more thanks.How do you start the process although I appreciate my CX3 is petrol and doesn't apply.
CX3 Sport Nav - Petrol - Auto - safety pack - snowflake white - 2019


1Monty
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Re: Diesel in Engine Oil

Post by 1Monty » Fri Jan 19, 2018 3:57 pm

Better still, buy a petrol.
SINCE FEB 2018 I NO LONGER OWN VEHICLE
CX-3 Sport Nav - 2.0L Petrol - 2017 - Manual - 2WD - Eternal Blue Metallic - Half Leather - 44.3mpg on a good day down hill with a strong wind behind 😎


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anchorman
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Re: Diesel in Engine Oil

Post by anchorman » Fri Jan 19, 2018 6:45 pm

DaveG wrote:
Fri Jan 19, 2018 2:17 pm
Anchorman that is interesting not sure how it works, if you have time can you explain more thanks.How do you start the process although I appreciate my CX3 is petrol and doesn't apply.
It’s quite easy to initiate using the same test point in the fuse box that is used for resetting the oil data. It should really only be done if the DPF light comes on as a result of the normal automatic regens fail to work. It’s slightly scary as the car ”goes off on one” and the neighbours won’t thank you for it. It should not be interrupted once started.

I can post a pdf but I don’t really want people dabbling. I prefer to email it if you want to pm me with your email address.
CX-5 Sportnav diesel auto. AWD


DaveG
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Re: Diesel in Engine Oil

Post by DaveG » Fri Jan 19, 2018 8:40 pm

Thanks anchorman, just wondered no need for further info as to I said I now have a petrol, Even if I didn't think I would stick with the Italian tune up.

Although as you said the static forced regen sbouldnt be interrupted, same problem I found on the road having to slow down during the drive lol.
CX3 Sport Nav - Petrol - Auto - safety pack - snowflake white - 2019


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