Hi Nodge
I have looked but can't find the 5W-40 in C1

I used this last oil change. Mine isn't DPF equipped, but this is still a mid SAPS oil, which has a 15% better load rating than the minimum allowed for a C1 oil.

https://www.opieoils.co.uk/p-206062-castro...e-oil.aspx

Also keep in mind that most garages simply buy the cheapest bulk oil they can find, and put it in everything that comes in for an oil change. When I worked in a franchise dealer, the oil was supplied by Elf, but we used just 1 drum at a time, hooked up to the oil pump system. From memory it was API SJ 10w40, but it was over 20 years ago now, so oil spec's have changed a bit.

Personally I always prefer a heavier oil which gives better mechanical protection, over a lighter oil which gives improved efficiency. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

Years ago I used to buy the engine oil for whatever car I had in 25ltrs, always used a standard fleet type but from a good known make.

With the coming of the Turbo, DPF, EGR I had to update the oil standards.


Fings aint what they used to be

An engine is an engine for the most part.
Vehicle manufacturers like to make vehicles look economical to run, so will use a thinner oil which has lower windage losses.
However as the manufacturers only give a relatively short warranty, they don't care if the engine fails later on in the vehicle's life.
Items like CATs and DPFs require an oil which has a reduced ash content when burnt, which is where low SAPS oils come in. However a slightly thicker oil with a medium SAPS rating shouldn't harm a CAT or DPF, and offer much better protection for the mechanical components in the engine.

Some engines are more prone to a particular wear issue, the VW PD was particularly susceptible to catastrophic cam follower wear if the correct oil wasn't used.
The D3/4 engine suffers bearing or crank failure, simply because the oil system is marginal at best, made worse by using a thin engine oil.
The oil should protect the engine, not cause it to fail early.

So I always use an oil which will provide better protection than the manufacturer says to use. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

The c1 standard has been replaced by the c4 standard, you just need to find a 5w40 c4 or low saps. Personally, examining my problem, I can deduce that it was a low quality material problem, a good oil can help but it does not solve the material quality problem

I'd agree, the valve stems used in these engines are particularly soft. They are easily dressed with a file, which proves they are very soft.
In years gone by, valve stems needed abrasion to flattern them off, as a file would simply skate over them.

An oil with a higher load capacity will help, but won't fully overcome a poor quality material choice. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

Nodge68 wrote:

All the DW12 engines use the same grade of oil, which is a 5w30 fully synthetic.
The only difference for a DPF engine is the oil needs to be a low ash formulation, so as to not soot up the DPF. The DPF engine still uses a 5w30 grade though.