Oil Smackdown: 5w-30 C1 vs 0w-30 A5/B5
 

Anyone with a Euro IV 180/185 D5 tried 5w-30 C1 as an alternative to 0w-30 A5/B5?

From my research the specs are very comparable however with the C1 the sulphated ash (known for blocking up emissions equipment) is less than half of that of A5/B5 spec oils.

Castrol 0w-30 A5/B5 Spec Sheet

Castrol 5w-30 C1 Spec Sheet

My rationale for switching -
I currently run 5w-30 A5/B5 of which there are a multitude of cheaper options than the rather monopolised and expensive Castrol 0w-30 A5/B5, no reason not to use it in the UK climate.
However if I can run my car on 5w-30 C1, in theory that will less frequently block the DPF that could potentially;

- Reduce DPF regenerations
- Increase Economy (more diesel injection is required during a regen)
- Minimise oil dilution with diesel and maintain protective viscosity for longer
- Minimise the event of an engine runaway from rising oil in the sump
(Though the ECU would warn you)


The Lubrizol Relative Performance Tool appears to support this theory (Select ACEA 2016 on the left and tick 'C1' and 'A5/B5').

I know there's some dogmatic Volvo owners on here but I'm frankly not interested in comments along the lines of;
"Volvo specify this oil, if you don't use it then your shells will implode, a rod will shoot out from your sump and your car will turn into vessel destined for Valhalla" :speechless-smiley-3

I am by no means an oil specialist but would be interested to hear the opinions of one or a like minded individual.

No!
C1 is NOT at all appropriate, these engines are not designed to run with such little anti-wear components in the oil.
The equivalent to A5/B5 would be C2, but it still isnt great in these engines, plus, contrary to seemingly apparent logic (nothing is straightforward with oil and engines) C spec oils can cause -more- dpf trouble in these than using the full saps A5/B5.
Add to that, whilst talking oil with millers and total, both stated not to use C soec oils in the D5. Im trying to wangle details as to their own reasoning, but they said do not use anything other than full saps very adamantly even though C spec should be backward compatible. (There are some reasons why it isnt always backwards compatible 100%)

Thanks for the firm reply Andy, I'm glad that you have pursued this with interest. The logic is seemingly baffling regards the C spec oils and more DPF problems... If you can expand on that any further I'd appreciate it, though an apparent lack of anti-wear components I do comprehend.
I usually run my car with an additive like Liqui Moly Ceratec or Archoil 9100/9200 but as it appears that the higher SAPS of an A5/B5 is required, in particular the phosphorus and sulfur for their anti-wear and antioxidative qualities then I guess I'll steer clear of the C1.

It has baffled many, and still does!
One explanation is that the mid/low saps gets burnt more easily amd actually loads the dpf with ash much more prominently than the full saps under certain conditions, so although the full saps is more poisonous, it can cause less trouble.
I dont recall all the detail, this is very recent news and isnt well established yet afaik, I need to do more study in this area to fully grasp the subject. This is a very vague summary of what has recently been found but gets the main point across.

That's a fair enough explanation and perhaps information that needs to be more widely spread. I've seen the AA and various websites stating "If you have a DPF you must use a low SAPS oil." which to the lesser informed or perhaps even curious person could lead to some trouble...

Nonetheless the oil change this week will be done using Fuchs Titan XTR 5w-30 A5/B5 and LiquiMoly Ceratec.

And thanks for chiming in Andy your comments have been helpful. :)

Not a prob!