Can't see a way to edit, so correction I bought Castrol Magnatec 5W40 C3.

That's what I've bought to use in my D350 for the next change. L405 D350 SE Carpathian Grey D5 19" rims

Checkout Cx oils ! Strange most other DPF/TWC equipped cars from major manufacturers specify C3 !

https://www.opieoils.co.uk/t-acea-car-engi...X-Ta7bTGjO

If I had a V6 I'd probably be using this
https://www.opieoils.co.uk/p-874-motul-810...e-oil.aspx
Expensive but likley it has a very good synthetic base stock which will protect the cranshaft better than the cheaper oils we can get away with in the V8's 2012 TDV8 Vogue (L322)

Mohawk wrote:

Checkout Cx oils ! Strange most other DPF/TWC equipped cars from major manufacturers specify C3 !

https://www.opieoils.co.uk/t-acea-car-engi...X-Ta7bTGjO

From your link Mohawk, I don't know what they're thinking over at Opie Oils, but their ACEA C4 summary is wrong on both counts...



As Gremlin has said all along, the holy grail for TD/SDV6 owners is a 5w/40 C4 (so higher 'hot' viscosity of 40, same low saps as a C1 for our DPF ash levels, yet a higher HTHS for better engine protection)

Jon 1992 RR Classic 3.9 efi Vogue
2014 Disco 4 HSE
===================
Both my fatties now gone...
Previous: 2011 L322 4.4 TDV8 Vogue SE /// 2002 L322 4.4 V8 HSE /// 2009 Discovery 3 2.7 TDV6 XS /// 2004 Defender 90 TD5 /// 1993 110 V8 Snatch Landrover /// 2005 Discovery 3 2.7 TDV6 SE (Aus) /// 1990 110 Isuzu 3.9 County (Aus) /// 1976 Series III Trayback (Aus)

Everything I've read so far says C1 whilst low SAPS was designed for fuel efficiency & as it apparently fell short is why it has been dropped. C4 is NOT a C1 replacement or the ACEA would state that.

JLR do NOT use any proprietary DPF technologies its the same as fitted to every other manufacturers & BMW being the closest EURO6 compliant diesel with all the same crap emissions reduction "ha" garbage has their late model Euro6 335D's using C3 same as most other manufacturers.

I'll check DPF regen mileage before & after I swap to see if there is any noticeable difference.

Smith & Allen do a C4 5w-30 with a slightly higher viscosity than their C1 5w-30 which may help if V6 crank failure is due to oil being too thin (which I doubt). C4 seems to be on paper a suitable substitute for C1 and was developed for 'highly stressed' engines which the V6 arguably is compared to the V8. It will take many 10's of thousands of miles before you would notice a significant reduction in DPF regen intervals as the extra ash buildup will be very slow. You could however see a change in mpg over a shorter time depending on how accuratley you monitored it before. 2012 TDV8 Vogue (L322)

Mohawk wrote:

Everything I've read so far says C1 whilst low SAPS was designed for fuel efficiency & as it apparently fell short is why it has been dropped. C4 is NOT a C1 replacement or the ACEA would state that.

Mohawk wrote:

JLR do NOT use any proprietary DPF technologies its the same as fitted to every other manufacturers & BMW being the closest EURO6 compliant diesel with all the same crap emissions reduction "ha" garbage has their late model Euro6 335D's using C3 same as most other manufacturers.

Mohawk wrote:

I'll check DPF regen mileage before & after I swap to see if there is any noticeable difference.

So that's where I was going when people were saying you can't use C3. The amounts of oil burned are tiny & the amount that becomes ash even less, so yes DPF will be affected over a long time. Either way the 40's 20% higher HTHS should work better on the bores & high torque, low RPM, low oil pressure regions, like when gassing it from low rpm.

I do tend to use the paddle's to drop one or two gears for quick overtakes, allowing the engine to spool up & avoiding the gearbox kick down lurch. The wife asked the other day do I always flash people before over taking ? Took me a minute to figure out what she was on about. She'd seen me down changing on the left paddle which is just by the indicator/light stalk ! 😂

I taught a friend about the paddles recently, he has been driving ZF autobox Audi's for forever & didn't know how to avoid kick down delay/lurch/stress nor how to re engage auto mode. For anyone interested, left paddle shifts down one gear per pull & puts car temporarily into manual mode, it will hold the selected gear until the rev limit then change up, unless you A. Manually change up earlier using the right paddle (or shift lever on side me ZF boxes) or B. Don't do anything for 30 seconds, at which point the box will switch back to full auto mode.
You can also select a lower gear for hill descent to control vehicle speed via engine braking like you would with a manual box.
To force auto mode back into play, just pull & hold right + paddle for 2 seconds👍

Mohawk wrote:

So that's where I was going when people were saying you can't use C3. The amounts of oil burned are tiny & the amount that becomes ash even less, so yes DPF will be affected over a long time. Either way the 40's 20% higher HTHS should work better on the bores & high torque, low RPM, low oil pressure regions, like when gassing it from low rpm.

I read an ACEA paper that concluded that a C3 oil will result in a 50% higher soot accumulation over and above that produced by running the same grade C1 oil. The testing was carried out on simulation rigs design to represent 180,000 miles of running. I suppose it stands to reason, given the ratio of SAPS content for C1 & C3 oils (0.5% m/m vs 0.8% m/m).

So if you expect an average DPF to require replacement or cleaning of soot at say 200K miles, that's been behind an engine running C1 oil, the same vehicle would require it's DPF cleaning / replacing at just 133K miles. So over the long term (and higher mileages) it does make a difference, plus as the DPF clogs, regens become more frequent and fuel consumption will therefore increase.

All of the above argument can all be traded off, of course, by the engine protection offered by a C3 oil. It just goes to show you can't have your cake and eat it, and I suppose the same is true of oil specification choice.

Jon 1992 RR Classic 3.9 efi Vogue
2014 Disco 4 HSE
===================
Both my fatties now gone...
Previous: 2011 L322 4.4 TDV8 Vogue SE /// 2002 L322 4.4 V8 HSE /// 2009 Discovery 3 2.7 TDV6 XS /// 2004 Defender 90 TD5 /// 1993 110 V8 Snatch Landrover /// 2005 Discovery 3 2.7 TDV6 SE (Aus) /// 1990 110 Isuzu 3.9 County (Aus) /// 1976 Series III Trayback (Aus)

I use C1 oil, but add Extralube ZX1 every oil change - have been doing this for 5 years on MY11 car which is coming up to 200,000 miles ( for me that is the best of both worlds, ZX1 is just worth it for my peace of mind when getting into higher mileages )

https://www.team-zx1.com/extralube-zx1-micro-oil/

Last edited by pcourtney on 15th Oct 2025 12:14am. Edited 1 time in total

Some very interesting debate, which was the point of my raising this thread, but may I respectfully remind members to try to not drift too far off topic, this thread is meant to be a technical discussion about oil, thanks all!  V6 Vogue - “Less is More” - less to go wrong!

JayGee wrote:

No way of knowing the ash level but the car will throw a code when there is not enough capacity left. You can also check the pressure differential voltage and reference it with the workshop test procedure under different loads and rpm's AFAIK the upper limit is 1.5v. Mine goes to 2.5v with hard acceleration so I'm getting mine cleaned now it's getting near 180k miles.

Good valid post there jaygee - mine is now 2.5v as well and edging towards 200,000 miles, will be looking at removing the DPF and getting it cleaned and put back in place after Xmas, have found a place local to me that can do it for £300