It is generally OK with most engines that you can vary the grade one step up or down and be OK. That may not be the OEMs point of view, but the data shows this to be true.
Examples: you car calls for 5w-20. But using 5w30 or 10w30 would be perfectly fine. or a 0w-20 or 0w30 as well.
I have over 650 used oil analysis on this 3.5L Duratech engine. It is a very robust engine in terms of wear. It only averages around 2ppm/1k miles of Fe at 5k miles, and actually drops down to 1.6ppm/1k miles at 10k mile OCI. The greatest concern you should have about this engine series isn't the oil you use; just pick a API SN 5w-20 or 30 grade and it will be fine. The biggest issue BY FAR is the water pump location (internal to the cam chain cover); if it leaks into the engine oil sump it will ruin the engine quickly if not discovered in a very timely manner. THAT is, by far and away, something to worry about more than oil grade.
I advocate for getting used oil analysis on this engine every 5k miles, once it goes over 75k miles of use. Track the coolant indicators closely; you can pretty much ignore the wear because it will be so low it will be incidental. Keep an eye on the coolant bottle and the UOA coolant indicators. If you get a MIL code (CEL, or whatever you want to call it), STOP THE ENGINE IMMEDIATELY and have it checked for codes which would indicate the timing chain/cams are out of sync. This is because the water pump is driven by the timing chain, and when the water pump starts to fail, it can get bad enough that the chain slop will alter the timing events on the variable cam drive.
Don't worry about the oil grade; WORRY ABOUT THE WATER PUMP.