hi,I'm very sorry to continue this well-known event in 2025. But there are new perspectives on this incident at present.
I browsed through the original factory maintenance manual and discovered an interesting thing that is rarely mentioned: oil pressure. And tests were conducted on five m156 units, and the results were astonishing. The original factory maintenance manual requires that the oil pressure should reach above 4.4bar at 3000RPM. However, on the five m156 units using 0w40, the oil pressure would never exceed 4.0bar, which is far below expectations!





And I used a micrometer to measure the bearing bush clearance, which was between 0.009mm and 0.01mm! The clearance of the bearing bush is extremely large,This is a pure racing car design, so if the engine oil is thin, the oil pressure will disappear at the crankshaft bearing. This is also why the m156 will wear out the camshaft and the hydraulic top barrel, and even destroy the bearing bush.

So I think m156 should use engine oil with a higher viscosity. Of course, all of this is just my guess. I hope it can draw attention and have some capable people participate in the discussion.

I never use any -0- weight oil. I always jump up to -5w-. Remember the engineers new what oil was going into all these engines when designing them but what a lot of people don't understand is the whole emission's thing.
-0w- oil was a break through for cleaner running and better miles per gallon. Why do you think they are now running 0W-10 and 0w-20 oil's ? That stuff is like water and has very little drag to it especially in the oil pump and actually frees up horsepower.

very good idea, bro.Although the viscosity of some 5w40 engines is higher than that of 0w40, there won't be a significant difference. This is bad news. I think 5w50 or even 10w60 engine oil can be used

You don't want to go too thick and 10-60 is way to thick. Remember the oil has to pump up to the top of the valve train very quickly so to thick is no good.

MB recommends only 0W40 or 5W40 be used in the M156. I always ran 5W40 (Shell Rotella T6 as it is high in ZDDP) and cheated a little and ran MOS2 as well in an attempt to reduce start up wear as my car always sat for long periods between uses and sat all winter (about 6 months).

Ive had mine since new and at 2 year old when I actually used the dealer for services they got told to switch to 5W40, they used Shell Helix Ultra which I have used ever since.