Originally Posted By: m37charlie
Originally Posted By: tommygunn
Because M1 0W-40 is not a mid-SAPS oil.
It (like all other high-SAPS oils) kills diesel particulate filters and clogs the exhaust gas recirculation system with soot.
Which is expensive (DPF) and/or time consuming (cleaning all the soot out of the pipes and EGR valve) to fix.
So manufacturers started to specify mid-SAPS oils to counteract that.
I beg to differ with the part of your comment pertaining to soot and EGR.
High SAPS oils do not form more soot, but engines calibrated for EGR do form more soot.
And engines with EGR but without DPF are perfectly capable of using high SAPS oils.
Typical CI4+ oils have 1.2-1.5% SA, the deposits in EGR valves are soot, and other fuel combustion products, NOT ash from oil.
Charlie
https://www.lubrizol.com/EngineOilAdditives/ACEA/ConferencePapers/LowerSAPS.pdf
Lubrizol begged to differ at the UEIL International Congress in 2006. On page 20/21 they show that in their testing, the use of Euro 3 (read: high-SAPS) compared to mid-SAPS oils yield:
- Increased piston deposit formation
- Increased particulate emmisions
- Increased clogging of the EGR piping by 42%
- 140% faster blocking of the DPF
- Exhaust back pressure over five times greater
- 1.5% increased fuel consumption
It's also true in the real world, you seldom see people with mid-SAPS oils clean their EGR system while there are a gazillion howtos for it on turbo diesels spec'd for high-SAPS as you get the engine check light all the time at >100K.
In a study from Total they link it to the (intended) oil consumption:
http://www.southernlubricants.co.uk/aqad...y%20Mode%5D.pdf