Hi, I've not experienced this on my FF but it did become quite a problem on our Mazda, that used regen on the exhast stroke and it became so much of a problem that the sump would fill up with diesel.

If you watched the fuel instant fuel consumption it would drop from 50+mpg down to 25 for 5 minutes, then jump back up again. Used so much fuel that instead of averaging 54mpg over a 1000 miles I'd be getting about 37 mpg, That's all fast cruising between Swindon & Reading and back on a daily basis.

I used to have to change the oil every 3 months because there was so much fuel in it. It became uneconomical at £150 a time and having to use special oil. In the end I just sold the car.

I've been keeping any eye on this ever since and every oil change sample the oil, I've so far not detected any diesel in the engine oil in the FF, but in the Mazda I'd get at least 1/2 litre adding between changes. Fuji White 2012 4.4 TDV8 Westmiinster

Alex1976 wrote:

Interesting info on the issue of oil dilution and the resultant engine failures in TDV6 and SDV8 engines.

https://rangeroverworld.co.uk/news

The only issue seems to be trying to find 5W40 oil that is C1 grade.

Hi, there seems to be some folks who are thinking fuel in the oil is down to failed DPF regenerations, this is not true, fuel gets into the sump during the exhaust stroke regardless of whether the regen is successful or not as the DPF is downstream of the exhaust port, i.e. the diesel (or most of it) has already passed through the engine before it reaches the DPF.

There is a case to say that if the engine is turned off that any unburnt fuel in the engine does not get blown out the exhaust and therefore trickles down into the sump, but this is also a false flag as the same would apply to normal operation when the engine switched off mid stroke regardless of if a regen were active or not.

The truth is, it happens because of porus rings, i.e. the better the ring sealing the less likely diesel is to get to the sump, worn rings, scored bores or in the occasional instance where the ring gaps actually align during the process will make the problem worse. a coked up engine is actually a good thing in this regard as there is less chance of unburnt fuel reaching the sump. Fuji White 2012 4.4 TDV8 Westmiinster

@AndyRoo:

You are not quite correct in what you say, during the regen process the engine is deliberately overfuelled. If the process is interrupted, it will reinitiate again and again until it succeeds. This extra fuel increases the dilution effect. The engine management algorithm takes account of this, and drops the MTS accordingly.

No-one is saying diesel from the exhaust can find its way into the sump, that’s absurd.

There are a few good reference articles on this subject which make interesting reading. “If it ain’t broke, don’t fix it” -where’s the fun in that?

Hi, thanks for the explanation, every day is a school day

Andy Fuji White 2012 4.4 TDV8 Westmiinster

How do the engines test for oil dilution?

I'm assuming there isn't a sensor specifically for measuring the amount of diesel in the oil, or is it as simple as an increase in oil level?

Has anyone tested their oil after 6k or 12k to really know the level of oil dilution? I know Millers Oils do a Oil Sample Analysis for £39.95 - send in 90ml of oil and they will tell you what is in there that shouldn't be. That might be worth having a go. Current:
- 2013 L405 4.4 TDV8 Vogue
Sold:
- 2004 L322 4.4 Vogue (BRC LPG)
- 2002 L322 4.4 HSE (having fixed timing chain guides)
- 2000 P38 4.6 Vogue (BRC LPG)
- 1981 2-door In-Vogue
- 1980 Ex-Army SIII LWB
- 1976 SIII LWB
- 1968 SIIA
Stripped for parts:
- 2003 L322 4.4 Vogue

Hi Zebedee,

As I said above, it’s algorithm based, the ECU looks at many different parameters and decides how the car has been driven, and calculates the expected dilution, it is not measured directly from one or two sensors.

There are a few articles on this, already posted on this forum, but can I hell find them!  “If it ain’t broke, don’t fix it” -where’s the fun in that?

I don't understand how you can over-fuel a diesel. They always run excess oxygen, so any excess fuel will just burn and deliver horsepower?!?!

Chris. L405 - 4.4SDV8 Vogue
P38 - 4.6V8 HSE
Land Rover series IIA V8

Hi ChrisJC,

It’s not strictly overfuelling, it’s called a “post injection”, meaning there is a second injection of fuel microseconds after each normal compression/ignition phase injection, which allows uncombusted fuel into the cylinders, thence the exhaust to the DEF for catalytic combustion to burn off the soot at around 600C-650C.

I will try to find the articles I spoke of, but how to post a document on here?

There are already links to these documents on this forum, but I can’t find them and can’t remember who posted them. “If it ain’t broke, don’t fix it” -where’s the fun in that?

Gremlin500 wrote:

Hi Zebedee,

As I said above, it’s algorithm based, the ECU looks at many different parameters and decides how the car has been driven, and calculates the expected dilution, it is not measured directly from one or two sensors.

There are a few articles on this, already posted on this forum, but can I hell find them!

Gremlin500 wrote:

Hi ChrisJC,

It’s not strictly overfuelling, it’s called a “post injection”, meaning there is a second injection of fuel microseconds after each normal compression/ignition phase injection, which allows uncombusted fuel into the cylinders, thence the exhaust to the DEF for catalytic combustion to burn off the soot at around 600C-650C.

I will try to find the articles I spoke of, but how to post a document on here?

There are already links to these documents on this forum, but I can’t find them and can’t remember who posted them.

Interesting - thanks!

That also explains why there is a butterfly in the air intake - something else for which there is no need on a Diesel engine.

Chris. L405 - 4.4SDV8 Vogue
P38 - 4.6V8 HSE
Land Rover series IIA V8

For those who are interested, a little light reading:

https://www.dropbox.com/s/d0bcrd7sve4l598/...d.pdf?dl=1

(should be 19 pages!).

Click image to enlarge

Thanks Kot!  “If it ain’t broke, don’t fix it” -where’s the fun in that?

My God you must have good eyes I can hardly read it
You could of course read page 1 where you will find a better copy which is just about more readable if you use magnify
https://www.fullfatrr.com/gallery/albums/u...lained.pdf 2018 SE SDV8 4.4 Byron Blue