Originally Posted by buster
Originally Posted by OIL_UDDER
Nice! As an former Pentastar design engineer I am slightly bias but the engine is really high quality. Few points from the development using tens of millions of dollars in analysis and testing regarding the oil and durability.....
The lighter oil was chosen
mostly for fuel economy BUT engineering is the science of compromise. You help one thing but hurt another.
A thicker oil will reduce timing chain and tensioner wear because the center timing chain idler doesn't go fully hydrodynamic till about 1650rpm on 5w-20. So, a thicker oil will lower that number slightly and with general loads/speeds the engine spends a lot of time around 1500-1750 rpm with the 8 speed. So thicker oil is a win there. Additionally, the earlier engines had what was called the "McDonald's Arches" in the idler bearing which was intended in making a more uniform distribution but in actuality acted as a knife edge. This design was changed around 2014 to a smooth bearing. So overall timing chain issues will likely follow the 2011-2014 engine years more than 2014+.
Where you lose.... The head is very complicated with a Type II valve train. Meaning lots of things to pressurize and pump up at start up. A thicker oil didn't do so well here (on long sit times +cold start) and contributed to a overall increased engine wear especially in the head and cam bearings.
Last point. This engine needs occasional WOT runs if you want it to last. Granny cycling is bad for it. So bad for it we actually created a new granny cycle test during the cylinder #3 misfire issue. The highest wear is in the valve guides, because of tight valve stem seals (for emissions, reduce oil burn). They basically dry out. When you go WOT/high rpm/load you get some fresh oil in there and this keeps the wear down. Thicker oil might not help this condition but we also change the valves/guides/seals in 2014+. Not sure the impact.
Cheers!
Kevin
PS. Turn off stop start and do not run e85 if you are concerned about engine wear. Eats the engine alive.
Thanks for sharing.
Sounds like a 20 grade with a higher HT/HS (such as Red Line) would be a nice choice for this engine (non api approved of course). Or an API approved 30 grade, most of which have a HT/HS of 3.-3.2.
I was just thinking that a 2.9hths from redline 0w20 would be the happy medium for sure.