4RRS wrote:

I manage to avoid failed regens 99% of the time, my problem is the interval between regens is painfully low, hence oil dilution due to many successful regens ultimately bringing down my service interval. As mentioned driving in France 650+ mile intervals, here 150-190 and then a regen. Would love to know why!!

The more the load in the car the better the chance of achieving 250C which of course will stretch out the distance between AR's but difficult to achieve keeping to speed limits
More relaxed driving styles – no towing or heavy loads, sticking to speed limits etc. – reduces the heat produced by the engine and increases soot production, filling the DPF faster and thereby requiring more frequent active regenerations. The 4.4L engine is such a low revving engine even if you drop down a gear to increase revs it has little effect and the auto gearbox usually upshifts after a few mins anyway.
I read somewhere there is a trigger at 250 miles, if no AR is completed in that mileage range, then its automatically triggered anyway.

Some light reading, note JLR did offer software updates for customers complaint about service intervals lifting the fuel dilution limit from 7% to 10% by volume. I believe its a recipe for disaster, dont ignore the service request.

https://www.fullfatrr.com/gallery/albums/u...ration.pdf 2018 SE SDV8 4.4 Byron Blue

Interesting reading, but can someone please explain to me exactly how unburned diesel gets into the sump from the Catalytic Converter?

“The second post injection is used to generate hydrocarbons by allowing unburnt fuel into the catalytic converter”

and

“Engine oil dilution can occur due to small amounts of fuel entering the crankcase during post injection phases”

So what’s the physical path? Assuming “Post” means after the compression/ignition phase, so the exhaust valves are opening, there should be little incentive for fuel under cylinder pressure to exit past the piston rings, surely it would all go down the exhaust (as intended)?

I’m just not getting it  “If it ain’t broke, don’t fix it” -where’s the fun in that?

Post injection does get past the piston rings when the engine is stopped, same as if an injector failed and dribbled fuel into the cylinder this was always the usual way before dpf's were fitted.

Think of it as the fuel is thinner and washes past the rings as the engine is stopped and cools, any exhaust pressure would have dissipated. 2018 SE SDV8 4.4 Byron Blue

@Kot:

I always greatly respect your opinion as you must already be aware, but if it happens when the engine is stopped, surely nothing significant can happen? On the other hand, maybe even if 0.00001ml of diesel passes the piston rings every revolution of the engine, at say 2500 rpm thats a huge number of tiny doses of diesel per hour of running. Obviously, there is NO direct path from the exhaust system back to the sump, as far as I know? “If it ain’t broke, don’t fix it” -where’s the fun in that?

When the engine is running the secondary injected fuel is burnt off as it's injected later and it is intended to be burnt in the dpf not the cylinder.
When the engine is stopped during an AR, momentarily, secondary fuel is still being injected into the cylinder and most of the fuel stays within the cylinder as there is now no exhaust flow.

A good explanation is here

https://www.castrol.com/en_gb/united-kingd...g%20use%20 2018 SE SDV8 4.4 Byron Blue

Today I did this:

Well done I can see your smile of satisfaction from here  2018 SE SDV8 4.4 Byron Blue

I know, I'm on my 3rd or 4th in 7000 miles.
Our cars are not fit for purpose its ridiculous.

I'm thinking I may well let it go next year as I've not used it much this year and I'm likely to use it even less in 2024. Whilst I love the car I'm also getting increasingly resentful at how much it costs to run with ever increasing insurance, warranty, marked depreciation and of the course multiple oil changes. It all adds up and it just takes the shine off.

 2017 Vogue SE
Citroen 2cv
Ferrari F430 F1 Spider

I agree but its difficult to find a match with a different manufacturer. Anything premium will always costs more to buy and run.

I'm going to contact JLR and ask if there was an update to the dilution levels from 7 to 10% before oil changes are required.

I've owned VW and Porsche suv's but they're not the same as a RR. I did own a Volvo XC70 a few years ago. The seats were very comfortable but still didnt have the spec.
Maybe the latest XC90 is better now. Although I did look at them before buying the RR and had read they have serious electrical issues, and a 2.0l engine.

The 7% or 10% doesn’t really matter so much, the point is not to let the dilution get that high in the first place, by changing the oil yourself (for about £35 if you have the kit). Ensuring the oil dilution is minimal, by more frequent oil changes and monitoring the regen status to prevent failed regens, is the way to go to reduce wear and tear and prolong the life of your engine.  “If it ain’t broke, don’t fix it” -where’s the fun in that?

I have been using the Kot Kit over the last couple of weeks resulting in no missed regens I only do short journeys in the winter due to not using my RR for towing our touring caravan so only 10/15 miles. For 287 miles driven my miles to next service has dropped 2350 miles[list=] My plan is to get the oil analysed next time i change to see what the oil dilution figure is. Has anyone done this?

Just an observation, my indie simply does a big service and a little service alternately every 12 months and I change the oil between services. I tried to follow the JLR service sheets but I've already done the 144,000 mile service despite having done nowhere near those miles as a result of having it serviced annually. But all fluids have been changed (gearbox, diff etc) and my "knuckles"checked. Geoff