[mos]

and two links for documents which could be interesting to read

1) Balancing of Engine Oil Components in a DI Diesel Engine with Exhaust Gas Aftertreatm
2) How Much ZDP is Enough?

 

[mos]

NOTE: my answer is combined from different sources over the NET and response from companies selling oil (not the best choice due the marketing bull*******g) and it's still confusing for me.

The straight forward answer to my question possibly doesn't exists, but "the C2/C3 oil will work, but it's not optimal for the engine life due the anti-wear additive levels". Poor performing lubricants can result in a non-catastrophic failure and may take years to surface. The best preventative measure that can be taken with any engine is to change the oil and use the best oil available. :facepalm:

I will try to explain that:

When you look at a technical spec of an oil, there are the contents of various elements, such as phosphorus, sulfur, calcium, zinc, magnesium etc. THE PURE ELEMENTS DO NOT EXIST IN THE ACTUAL OIL; it is the complex oil-soluble molecules which do the anti-wear, detergency, antioxidant activities.

ACEA C1/C2/C3/C4 =
- "low SAPS" oils which in fact are oils with less Zn, Ca, Mg, Mo .... all of which are present
in high performance additives usually used in non ACEA C class oils
- "low SAPS" oils means that there are less components in the combustion and this optimizes post-treatment system operation.

Most oils use a zinc additive package, which does provide a satisfactory performance in anti-wear applications. Low-zinc additives do provide a compromise between the anti-wear requirements and the anti-corrosion. That means, the original anti-wear protection has to be provided by an ash-less type of additive, because anti-wear protection still is a requirement - and to fulfill that need additives are required - but of another nature and possibly less efficient (now I expect somebody from FUCHS shooting me in the leg).

ZDDP = zinc dialkyl dithiosphosphate = the zinc (Zn) and phosphorus (P) that makes up the anti-wear additive. Many products are referring to the ZDDP, which is "the most effective combined anti-wear and anti-oxidant additives currently available." btw. zinc has no effect on the engine; it just holds the ZDDP molecule together, right?

Very high zinc oils are NOT a good idea at all! Excessive Zn and P levels cam result in additional wear.

It is possible to make a zinc-free engine oil with excellent anti-wear /antioxidant performance….at a price. see "zinc free oil" by FUCHS. in this particular case ZDDP has not been removed from oil, the latest spec has reduced ZDDP levels, but it is still present. Btw a lot of discussions of the web, hit Google with "How Much ZDP is Enough?"

Some number examples for a zinc free oil and Acea classes:
============================================================
TITAN GT1 5W-30 (zinc free oil)
Sulphated ash % 0.79
Phosphorus % 0.05
Sulphur % 0.19

C1-08
Sulphated Ash ≤ 0.5
Phosphorus ≤ 0.05
Sulphur ≤ 0.2

C2-08
Sulphated Ash ≤ 0.8
Phosphorus ≥ 0.070 and ≤ 0.090
Sulphur ≤ 0.3

C3-08 the same like C2, but higher HTHS ≥ 3.5)
Sulphated Ash ≤ 0.8
Phosphorus ≥ 0.070 and ≤ 0.090
Sulphur ≤ 0.3

C4-08
Sulphated Ash ≤ 0.5
Phosphorus ≤ 0.090
Sulphur ≤ 0.2

API SM Phosphorus ≥ 0.060 and ≤ 0.080 however the limit applies to 0w-20, 0w-30l 5w-20, 5w-30, 10w-30
API SL Phosphorus ≥ 0.10 and ≤ 0.12

But I cant find limit of Phosphorus for diesel oils only Sulphur.

API SM/SL section and old cars
==============================

Some say that API SM oil is worse compared to API SL oils when driving in town, mostly for older cars. The testing indicates that the current level of ZDDP in modern passenger car motor oils is more than enough to protect older engines as well.

API SM test
PASS: Average cam-plus-lifter wear < 60 μm maximum

API SL test
PASS: Average cam-plus-lifter wear < 20 μm maximum

The valve wear sequence tests above are different and so not readily comparable, that's where the room for argument is.

 

[mos]

Maybe you already found these documents, there's a lot explained, but not all is clear to me. This is a quote:

C3

Stable, stay-in-grade oil intended for use as catalyst compatible oil in vehicles with DPF and TWC in high performance car and light van diesel and gasoline engines. These oils will increase the DPF and TWC life. Warning: these oils may be unsuitable for use in some engines. Consult owner manual or handbook if in doubt.
This is where I found the quote:
http://www.acea.be/images/uploads/pub/070308_ACEA_sequences_2007_LD_and_HD.pdf

​

hi, definitely it's (ACEA web) the place where I was looking first. The C class is here to decrease/define the amount of SAPS which together with DPFs are designed to reduce particulate matter emissions from diesel engines (in fact the class is allowing DPF to work). opcorn:

 

[mos]

I would assume the C3 oils designed for DPF equipped cars offer less engine protection due to lower amounts of addatives.I would think they're still a perfectly acceptable option for any diesel engine unless specifically advised against in the car's handbook.

I always select castrol edge 0w-30 (not diesel edge) for my UK non DPF Civic.

cb550, thank you for the response. Definitely all C* oils do contain less additives to produce less SAPS. C class = low SAPS (Sulphated Ash, Phosphorous, Sulphur) additives can block the filter with ash.

I didn't find the "ultimate" answer yet, but regarding the SHELL HELIX ULTRA EXTRA. it's the recommended alternative for the DPF civic version. we have to keep in mind that the engines are the same between DPF/non-DPF versions. so the oil is still a good option, but not sure if it is the best one.

--
Martin