Doesn't matter what brand was used before either- run what you like best. And run whatever it says in the manual. Internet engineers never built anything...
While true, today's owner manuals are heavily influenced by CAFE standards. Only the oil weight used in gov't testing to achieve the mpg rating can be recommended in the manual.
Note: I am not saying to go against the manual here, if that's what you think is best.
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The following may go against popular opinion, so:
**Flame Suit on**
Just saying that there's a wider spread of viscosities that can be safely used.
Example: we have a Jeep JL and a Toyota FJ.
FJ recommends 0w20 in the US, but everywhere else in the world can go up to 20w50, depending on expected minimum temperature. Toyota's manual even says that for heavy usage - towing, mountains, high speed etc, a thicker oil "may be a better choice"...but they can only mention 0w20 in the manual because of CAFE regulations.
In the Jeep 2.0T, manual says 5w30. But in this Stellantis engine in Europe, heavier oils are allowed.
For both, I run 0w40 winter and 10w40 summer with zero issues, and no loss of power or mpg.
I realize neither is the Pentastar 3.6; however for that engine I'd likely use at least a 5w30 - that was the original specification although there have been changes made to the design.
Some that "go against the manual" use the specified oil during warranty and switch later. Some switch when they get home from the dealer.
You certainly can't go wrong with the owner manual specification; but for myself, I choose to use a thicker oil - one that's specified or allowed for the same engine in other parts of the world.
I'm also speculating that with the new laws coming out relaxing mpg requirements and possibly doing away with the stop/start nonsense, that we may see heavier weight oil recommendations coming back to the owner manuals.
