Buster: there are many owners that you will never hear about or see that have switched to a 0W-30 or 5W-30 weight with zero issues.
No matter what anybody thinks or says there is nothing internally within the 5.7L (mechanically) that has the sensitivity or the knowledge that can physically tell the difference in the oils viscosity----> between the 5W-20 or 0W-20 compared to 0W-30 or 5W-30.
My 5.7L operates @ all temps extremely smooth & quite with 0W-40 within the crankcase.
I'm sure there will still be a few that are thinking the MDS system can do that.
This has been proven over and over and over it does not have that capability. Now some have rumbled that this system functions & is sensitive to Oil PSI. Maybe? Maybe Not! I never noticed any difference in psi between 0W-20/5W-20 in reference to PUP 5W-30.
Now with the SRT 0W-40 oil psi is a bit higher at all temps.
It is a very interesting word association game between recommend and require.
(Recommend) is a very easy word just to throw out there and use.
(Require) has a whole Nother cabinet of goodies that comes along behind it. You do not see this word just tossed out there within the lubrication industry.
My owners manual states basically the same thing if a 5W-20 is not available or cannot be found a 5W-30 can be used.
SyN Disclaimer: These are only my personal experiences & opinions. I have experienced Zero issues or strange bumps in the night!
I'm in No way shape or form looking or asking for anyone's approval or negative attitude due to I don't use what YOU use or do as YOU do!
